11 SOUND 19-35
18 TECHNOLOGY 174-192
GLOSSARY 193-197
















  1. Which of the following is an example of simple harmonic motion?

(a) the motion of simple pendulum ”                                                                                      (b) the motion of ceiling fan                                                                                                      (c) the spinning of the Earth on its axis                                                                            (d) a bouncing ball on a floor .

  1. If the mass of the bob of a pendulum is increased by a factor of 3, the period of the pendulum‘s motion will

(a) be increased by a factor of 2                                 (b) remain the same                                                   (c) be decreased by a factor of2                         (d) be decreased by a factor of 4

iii. Which of the following devices can be used to produce both transverse and longitudinal waves?

(a) a string                                                               (b) a ripple tank                                                     (c) a helical spring (slinky)                                           (d) a tuning fork

  1. Waves transfer

(a) energy                                                                (b) frequency                                                               (c) wavelength                                                         (d) velocity

  1. Which of the following is a method of energy transfer?

(a) conduction                                                      (b) radiation                                                            (c) wave motion                                                            (d) all of these

  1. In a vacuum, all electromagnetic waves have the same

(a) speed                                                                 (b) frequency                                                        (c) amplitude                                                           (d)wavelength

vii. A large ripple tank with a vibrator working at a frequency of 30 Hz-produces 25 complete waves in a distance of 50 cm. The velocity of the wave is

(a) 53 cm s-1                                                                 (b) 60 cm s-1                                                                (c) 750 cm s-1                                                              (d) 1500 cm s-1

viii. Which of the following characteristics of a wave is independent of the others?

(a) speed                                                                  (b) frequency                                                                                  (c) amplitude                                                           (d) wavelength

  1. The relation between v, f and ʎ of a wave is

(a) vf = ʎ                           (b) f ʎ =v                                                                                                    (c) V ʎ=                                                                            f(d) v= ʎ /f








  1. What is simple harmonic motion? What are the necessary conditions for a body to execute simple harmonic motion?
  2. Think of several examples of motion in everyday life that are simple harmonic.
  3. What are damped oscillations. How damping progressively reduces the amplitude of oscillation?
  4. How can you define the term wave?” Elaborate the difference between mechanical and electromagnetic waves. Give examples of each.
  5. Distinguish between longitudinal and transverse waves with suitable examples.
  6. Draw a transverse wave with an amplitude of 2 cm and a wavelength of4 cm. Label a crest and trough on the wave.
  7. Derive a relationship between velocity, frequency and wavelength of a wave. Write a formula relating velocity of a wave to its time period and wavelength. Waves are the means of energy transfer without transfer of matter. Justify this
  8. statement with the help of a simple experiment.
  9. Explain the following‘ properties of waves with reference to ripple tank experiment: a. Reflection b. Refraction c. Diffraction
  10. Does increasing the frequency of a wave also increase its wavelength? lf not, how are these quantities related?



  1. If the length of a simple pendulum is doubled, what will be the change in its time period?
  2. A ball is dropped from a certain height onto the floor and keeps bouncing. ls the motion of the ball simple harmonic? Explain.
  3. A student performed two experiments with a simple pendulum. He/She used two bobs of different masses by keeping other parameters constant. To his/her astonishment the time period of the pendulum did not change! Why?
  4. What types of waves do not require any material medium for their propagation?
  5. Plane waves in the ripple tank undergo refraction when they move from deep to shallow water. What change occurs in the speed of the waves?”







  1. The time period of a simple pendulum is 2 s. What will be its length on the Earth? What will be its length on the Moon if gm =ge/6? where ge = 10 ms-2. (1.02 m, 0.17 m)
  2. A pendulum of length 0.99 m is taken to the Moon by an astronaut. The period of the pendulum is 4.9 s. What is the value of g on the surface of the Moon? (1.63 m 5″)
  3. Find the time periods of a simple pendulum of 1 metre length, placed on Earth and on Moon. The value ofg on the surface of Moon is 1/6th of its value on Earth, where ge is 10 m 5
  4. A simple pendulum completes one vibration in two seconds. Calculate its length, when g= 1O.Oms-2
  5. If 100 waves pass through a point of a medium in 20 seconds, what is the frequency and the time period of the wave? If its wavelength is 6 cm, calculate the wave speed. (Ans: 5 Hz ,0.2 s ,0.3 s ms-1)
  6. A wooden bar vibrating into they water surface in a ripple tank has a frequency of 12 Hz. The resulting wave has a wavelength of3 cm. What is the speed of the wave? (Ans: 0.36 ms-1)
  7. A transverse wave produced on a spring has a frequency of 190 Hz and travels along the length of the springof90 m, in 0.5 s. (a)What is the period of the wave?           (b)What is the speed of the wave?                         (c)What is the wavelength of the wave
  8. Water waves in a shallow dish are 6.0 cm long. At one point, the water moves up and down at a rate of4.8 oscillations per second. (a) What is the speed of the water waves?                                                         (b)What is the period of the water waves? ( Ans: 0.29 ms-1 , 0.21 s)
  9. At one end of a ripple tank 80 cm across, a 5 Hz vibrator produces waves whose wavelength is 40 mm. Find the time the waves need to cross the tank. (Ans: 4s)
  10. What is the wavelength of the radio waves transmitted by an FM station at 90 MHz? Where 1M=1O 6 and speed of radio wave is 3×108 ms-1. (Ans: 3.33m)











11 SOUND 19-35



i- Which is an example of a longitudinal wave?

(a) sound wave    (b) light wave  (c) radio wave (d)water wave

ii- How does sound travel from its source to your ear?

(a) by changes in air pressure  (b) by vibrating in wires or strings                                                                                                                        (c)by electromagnetic wave     (d) by infrared waves

iii- Which form of energy IS sound?

(a) Electrical   (b)mechanical          (c) thermal             (d) chemical

iv- Astronauts in space need to communicate with each other by radio links because

(a)sound waves travel very slowly in space                                                                          (b) sound waves cannot travel in space     wavelength                                                           (c)sound waves travel very fast in space                                                                                      (d) sound waves have low frequency in space crease?

  1. loudness of a sound is most closely related to its

(a) frequency  (b) period  (c) wavelength                (d)amplitude

  1. For a normal person, audible frequency range for sound wave lies between

10 Hz and 10 kHz  (b)20 Hz and 20 kHz  (c)25 Hz and 25 kHz  (d) 30 Hz and 30 kHz

vii. When the frequency of a sound wave is increased, which of the following will

  1. wavelength ii. period ii. amplitude

(a) i only  (b) iii only   (c)i and ii only      (d) i and iii only


  1. What is the necessary condition for the production of sound?
  2. What is the effect of the medium on the speed of sound? In which medium sound travels more faster: air, solid or liquid? Justify your answer.
  3. How can you prove the mechanical nature of sound by a simple experiment?
  4. What do you understand by the longitudinal wave? Describe the longitudinal nature of sound waves.
  5. Sound is a form of wave. List at least three reasons to support the idea that sound is a wave.
  6. We know that waves manifest phenomenon of reflection, refraction and diffraction. Does sound also manifest these characteristics?
  7. What is the difference between the loudness and intensity of sound? Derive the relationship between the two.
  8. On what factors does the loudness of sound depend?
  9. What do you mean by the term intensity level of the sound? Name and define the unit of intensity level of sound.
  10. What are the units of loudness? Why do we use logarithmic scale to describe the range of the sound intensities we hear?
  11. What is difference between frequency and pitch? Describe their relationship graphically.
  12. Describe the effect of change in amplitude on loudness and the effect of change in frequency on pitch of sound.
  13. If the pitch of sound is increased, what are the changes in the following? (a)the frequency                                                    (b) the wavelength                                                           (c) the wave velocity                                              (d) the amplitude of the wave
  14. lf we clap or speak in front of a building while standing at a particular distance, we rehear our sound after sometime. Can you explain how does this happen?
  15. What is the audible frequency range for human ear? Does this range vary with the age of people? Explain.
  16. Explain that noise is a nuisance.
  17. Describe the importance of acoustic protection.
  18. What are the uses of ultrasound in medicine?


  1. Why two tin cans with a string stretched between them could be better way to communicate than merely shouting through the air?
  2. We can recognize persons speaking with the same loudness from their voice. How is this possible?
  3. You can listen to your friend round a corner, but you cannot watch him/her. Why?
  4. Why must the volume of a stereo in a room with wall-to-wall carpet be tuned Higher than in a room with a wooden floor?
  5. A student says that the two terms speed and frequency of the wave refer to the same thing. What is your response?
  6. Two people are listening to the same music at the same distance. They disagree on its loudness. Explain how this could happen.
  7. ls there any difference between echo and reflection of sound? Explain.
  8. Will two separate 50 dB sounds together constitute al00 dB sound? Explain.
  9. Why ultrasound is useful in medical field?









  1. A normal conversation involves sound intensities of about 3.0 X 10-6 W m-2. What is the decibel level for this intensity? What is the intensity of the sound for 100 dB? (Ans. (64.8 dB,0.01 W m-2)
  2. lf at Anarkali Bazar Lahore, intensity level of sound is 80 dB, what will be the intensity of sound there? (Ans: 10-4 Wm-2)
  3. At a particular temperature, the speed of sound in air is 330 m s”. lf the wavelength a note is 5 cm, calculate the frequency of the sound wave. ls this frequency in the audible range of the human ear? Ans. (6.6×103 Hz, Yes)
  4. A doctor counts 72 heartbeats in 1 min. Calculate the frequency and period of the heartbeats. Ans.(1.2 Hz. 0.83 s)
  5. A marine survey ship sends a sound wave straight to the seabed. It receives an echo 1.5“s later. The speed of sound in sea water is 1500 m s”. Find the depth of the sea at this position. Ans:(1125m)
  6. A student clapped his hands near a cliff and heard the echo after 5 s. What is the distance of the cliff from the student if the speed of the sound is taken as 346 ms-1? Ans. (865 m)
  7. A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s. lf the speed of ultrasound through seawater is 1531 ms-1, what is the distance of the seabed from the ship? Ans: (2618 m)
  8. The highest frequency sound humans can hear is about 30,000 Hz. What is the wavelength of sound in air at this frequency at a temperature of 20 °C? What is the wavelength of the lowest sounds we can hear of about 20 Hz? Assume the speed of sound in air at 20 °C is 343ms-1. (1.7x 10-2m, 17.2m)
  9. A sound wave has a frequency of 2 kHz and wavelength 35 cm. How long will it take to travel 1.5 km? (2.1 s)



















  1. Which of the following quantity is not changed during refraction of light?

(a) its direction    (b) its speed  (c) its frequency  (d) its wavelength

  1. A converging mirror with a radius of 20 cm creates a real image 30 cm from the mirror. What is the object distance?

(a) -5.0 cm  (b) -7.5 cm   (c) -15 cm       (d) -20 cm

  1. An object is placed at the centre, of curvature of a concave mirror. The image produced by the mirror is located

(a) out beyond the centre of curvature.    (b)  at the centre of curvature.                                                                                      (c) between the centre of curvature and the focal point  (d) at the focal point

iii. An object is 14 cm in front of a convex mirror. The image is 5.8 cm behind the mirror. What is the focal length of the mirror?

(a) -4.1 cm    (b) -8.2 cm   (c) -9.9 cm          (d) -20 cm

iv.The index of refraction depends on .

(a) the focal length                                                       (b) the speed of light                                               (c) the image distance                                           (d) the object distance

  1. Which type of image is formed by a convex)’ lens on a screen?

(a) inverted and real                                           (b)inverted and virtual                                                                               (c) upright and real                                                 (d) upright and virtual

vii. Which type of image is produced by the converging lens of human eye if it views a distant object?

(a) real, erect, same size                                              (b) real, inverted; diminished                             (c) virtual, erect, diminished                               (d) virtual, inverted, magnified

viii. Image formed by a camera is

(a) real, inverted, and diminished                        (b) virtual, upright and diminished                  (c) virtual, upright and magnified                      (d) real, inverted and magnified

  1. If a ray of light in glass is incident on an air surface at an angle greater than the critical angle, the ray will

(a) refract only                                                                  (b) reflect only                                                       (c) partially refract and partially reflect                (d) diffract only

  1. The critical angle for a beam of light passing from water into air is 48.8 degrees. This means that all light rays with an angle of incidence greater than this angle will be.

(a) absorbed                                                                   (b) totally reflected                                               (c) partially reflected and partially transmitted                                                             (d) totally transmitted




  1. What do you understand by reflection of light? Draw a diagram to illustrate Reflection at a plane surface.
  2. Describe the following terms used in reflection: (i)normal (ii) angle of incidence (iii) angle of reflection
  3. State laws of reflection. Describe how they can be verified graphically.
  4. Define refraction of light. Describe the passage of light through parallel-sided transparent material.
  5. Define the following terms used in refraction: (i) angle of incidence (ii) angle of refraction
  6. What is meant by refractive index of a material? How would you determine the refractive index of a rectangular glass slab?
  7. State the laws of refraction of light and show how they may be verified using Rectangular glass slab and pins.
  8. What is meant by the term total internal reflection?
  9. State the conditions for total internal reflection.
  10. What is critical angle? Derive a relationship between the critical angle and the refractive index of a substance.
  11. What are optical fibres? Describe how total internal reflection is used in light propagating through optical fibres.
  12. Define the following terms applied to a lens: (i)principal axis(ii)optical centre (iii)focal length
  13. What is meant by the principal focus of a (a) convex lens (b) concave lens? Illustrate your answer with ray diagrams.
  14. Describe how light is refracted through convex lens.
  15. With the help of a ray diagram, how you can show the use of thin converging lens as a Magnifying glass.
  16. A coin is placed at a focal point of a converging lens. Is an image formed? What is its nature?
  17. What are the differences between real and virtual images?
  18. How does a converging lens form a virtual image of a real object? How does a diverging lens can form a real image of a real object?
  19. Define power of a lens and its units.
  20. Describe the passage of light through a glass prism and measure the angle of deviation.
  21. Define the terms resolving power and magnifying power.
  22. Draw the ray diagrams of (i) simple microscope (ii) compound microscope (iii) refracting telescope
  23. Mention the magnifying powers of the following optical instruments: (i) simple microscope (ii) compound microscope (iii) refracting telescope
  24. Draw ray diagrams to show the formation of images in the normal human eye.
  25. What is meant by the terms nearsightedness and farsightedness? How can these defects be corrected?


A man raises his left hand in a plane mirror, the image facing him is raising his right hand. Explain why.

in your own words, explain why light waves are refracted at a boundary between two materials.

Explain why a fish under water appears to be at a different depth below the surface than it actually is. Does it appear deeper or shallower?

Why or why not concave mirrors are suitable for makeup?

Why is the driver’s side mirror in many cars convex rather than plane or concave?

When an optician‘s testing room is small, he uses a mirror to help him test the

eyesight of his patients. Explain why.

How does the thickness of a lens affect its focal length?

Under what conditions will a converging lens form a virtual image?

Under what conditions will a converging lens form a real image that is the same size as the object?

Why do we use refracting telescope with large objective lens of large focal length?


  1. An object 10.0 cm in front of a convex mirror forms an image 5.0 cm behind the mirror. What is the focal length of the mirror? Ans. (-10 cm)
  2. An object 30 cm tall is located 10.5 cm from a concave mirror with focal length 16 cm. (a) Where is the image located? (b) How high is it? Ha) 39.-54919? ANS: (a) 30.54 cm (b) 87.26 cm
  3. An object and its image in a concave mirror are of the same height, yet inverted, when the object is 20 cm from the mirror. What is the focal length of the mirror? Ans:10cm)
  4. Find the focal length of a mirror that forms an image 5.66 cm behind the mirror of an object placed at 34.4 cm in front of the mirror. ls the mirror concave or convex? Ans: -6.77 cm, canvas mirror
  5. An image of a statue appears to be 11.5 cm behind a concave mirror with focal length 13.5 cm. Find the distance from the statue to the mirror. Ans: 77.62 cm
  6. An image is produced by a concave mirror of focal length 8.7 cm. The object’ is 13.2 cm tall and at a distance 19.3 cm from the mirror. (a) Find the location and height of the image. (b) Find the height of the image produced by the mirror if the object is twice as far from the mirror. Ans:(a)15.84 cm, 10.83 cm (b)5.42 cm
  7. Nabeela uses a concave mirror when applying makeup. The mirror has a radius of curvature of 38 cm. (a) What is the focal length of the mirror? (b) ‘Nabeela is located 50 cm from the mirror. Where will her image appear? (c) Will the image be upright or inverted? Ans: (a)19 cm, (b)30.64 cm, (c)inverted
  8. An object 4 cm high is placed at a distance of 12 cm from a convex lens of focal length 8 cm. Calculate the position and size of the image. Also state the nature of the image. Ans: 2 cm,8cm,image is real, inverted and magnified
  9. An object 10 cm high is placed at a distance of 20 cm from a concave lens of focal length 15 cm. Calculate the position and size of the image. Also, state the nature of the image. (Ans: -8.57 cm,4.28cm, image is inverted, erect and diminished)
  10. A convex lens of focal length 6 cm is to be used to form a virtual image three times the size of the object. Where must the lens be placed? Ans: 4cm
  11. A ray of light from air is incident on a liquid surface at an angle of incidence 35°. Calculate the angle of refraction if the refractive index of the liquid is 1.25. Also calculate the critical angle between the liquid air inter-face. (Ans: 27.31,53.13 )
  12. The power of a convex lens is 5 D. At what distance the object should be placed from the lens so that its real and 2 times larger image is formed. Ans:30cm





















  1. A positive electric charge ;

(a) attracts other positive charge                           (b) repels other positive charge                                (c) attracts a neutral charge                                 (d) repels a neutral charge

  1. An object gains excess negative charge after being rubbed against another object, which is:

(a) neutral (b) negatively charged(c) positively charged         (d)  either a, b or c

iii. Two uncharged objects A and B are rubbed against each other. When object B is placed near a negatively charged object C, the two objects repel each other, Which of the following statements is true about object A?

(a) remains uncharged                                                 b) becomes positively charged                                   (c) becomes negatively charged                             (d) unpredictable

  1. When you rub a plastic rod against your hair several times and put it near some bits of paper, the pieces of papers are attracted towards it. What does this observation indicate?

(a) the rod and the paper are oppositely charged                                                                                       (b) the rod acquires a positive charge C (c) the rod and the paper have the same charges                                                         (d) the rod acquires a negative charge

  1. According to Coulomb’s law, what happens to the attraction of two oppositely charged objects as their distance of separation increases?

(a) increases   (b) decreases  (c)  remains unchanged   (d)  cannot be determined

  1. The Coulomb’s law is valid for the charges which are

(a) moving and point charges                         (b)  moving and non-point charges                    (c) stationary and point charges                    (d) stationary and large size charges

vii. A positive Wanda negative charge are initially 4 cm apart. When they are moved closer together so that they are now only 1 cm apart, the force between them is

(a) 4 times smaller than before                          (b) 4 times larger than before                                (c)  8 times larger than before                         (d) 16 times larger than before

viii. Five joules of work is needed to shift 10 C of charge from one place to another. The potential difference between the places is

(a) o.5V  (b) 2V  (C)  5V       (d) 10V

  1. Two small charged spheres are separated by 2 mm. Which of the following would produce the greatest attractive force?

(a) +1q and +4q   (b) -1q and – 4q      (c) +2q and +2q         (d) +2q and -12q

  1. Electric field lines

(a) always cross each other           (b) never cross each other                                      (c) cross each other in the region of strong field                                                                 (d) cross each other in the region of weak field

  1. Capacitance’ is defined as

(a) VC     (b) Q /V  (C) QV    (d) V/Q


  1. How can you show by simple experiments that there are two types of electric charges?
  2. Describe the method of charging bodies by electrostatic induction.
  3. How does electrostatic induction differ from charging by friction?
  4. What is gold leaf electroscope? Discuss its working principle with a labeled diagram.
  5. Suppose you have a glass rod which becomes positively charged when you rub it with wool. Describe how would you charge the electroscope (i) negatively (ii) positively.
  6. With the help of electroscope how you can find presence of charge on a body.
  7. Describe how you would determine the nature of the charge on a body by using electroscope.
  8. Explain Coulomb’s law of electrostatics and write its mathematical form.
  9. What is meant by electric field and electric intensity?
  10. ls electric intensity a vector quantity? What will be its direction?
  11. How would you define potential difference between two points? Define its unit.
  12. Show that potential difference. can be described as energy transfer per unit charge between the two points.
  13. What do you mean by the capacitance of a capacitor? Define units of capacitance.
  14. Derive the formula for the equivalent capacitance for a series combination of a number of capacitors.
  15. Discuss different types of capacitors.
  16. What is difference between variable and fixed type capacitor?
  17. Enlist some uses of capacitors.
  18. Discuss one application of static electricity.
  19. What are hazards of static electricity?







  1. An electrified rod attracts pieces of paper. After a while these pieces fly away! Why?
  2. How much negative charge has been removed from a positively charged electroscope, if it has a charge of 7.5 x10-11 C ?
  3. In what direction will a positively charged particle move in an electric field?
  4. Does each capacitor carry equal charge in series combination? Explain.
  5. Each capacitor in parallel combination has equal potential difference between its two plates. Justify the statement.
  6. Perhaps you have seen a gasoline truck trailing a metal chain beneath it. What purpose does the chain serve?
  7. If a high-voltage power line fell across your car while you were in the car, why should you not come out of the car?
  8. Explain why, a glass rod- can be charged by rubbing when held by hand but an iron rod cannot be charged by rubbing, if held by hand?


  1. The charge of how many negatively charged particles would be equal to 100 C.

Assume charge on one negative particle is 1.6 x10-19 C ? Ans: 6.25 x10-14

  1. Two point charges q,= 10 C and q,= 5 C are placed at a distance of 150 cm. What will be the Coulomb’s force between them? Also find the direction of the force.   (0.2 N, the direction of repulsion)
  2. The force of repulsion between two identical positive charges is 0.8 N, when the charges are 0.1 m apart. Find the value of each charge. Ans. (9.4 X 10-7 C)
  3. Two charges repel each other with a force of 0.1 N when they are 5 cm apart. Find the forces between the same charges when they are 2 cm apart. Ans. (0.62 N)
  4. The electric potential at a point in an electric field is 10“ V. If a charge of +100 C is brought from infinity to this point. What would be the amount of work done on it? (1J)
  5. A point charge of +2.C is transferred from a point at potential 100 V to a point at potential 50 V. What would be the energy supplied by the charge? (1001)
  6. A capacitor holds 0.06 coulombs of charge when fully charged by a 9 volt battery. Calculate capacitance of the capacitor. (6.67 x 10-3 F)
  7. A capacitor holds 0.03 coulombs of charge when fully charged by a 6 volt battery. How much voltage would be required for it to hold 2 coulombs of charge? Ans.(400V)
  8. Two capacitors of capacitances 6 F, and 12 F are connected in series with 12 V battery. Find the equivalent capacitance of the combination. Find the charge and the potential difference across each capacitor. Ans. (4 F, 48 p C, 8 V, 4V)
  9. Two capacitors of capacitances 6 F and 12 F are connected in parallel with a 12 V battery. Find the equivalent capacitance of the combination. Find the charge and the potential difference across each capacitor. Ans. (18 F, 72 C, 144 C, 12 V









































  1. An electric current in conductors is due to the flow of

(a) positive ions  (b) negative ions    (c) positive charges    (d) free electrons

  1. What is the voltage across a 6 resistor when 3 A of current passes through it?

(a) 2 V  (b) 9 V   (c) 1s v    (d)  36 v

iii. What happens to the intensity or the brightness of the lamps connected in series as more and more lamps are added?

(a) increases   (b) decreases  (c)  remains the same   (d) cannot be predicted

  1. Why should household appliances be connected in parallel with the voltage source?

(a) to increase the resistance of the circuit                                                                      (b) to decrease the resistance of the circuit                                                                        (c) to provide each appliance the same voltage as the power source                                     (d) to provide each appliance the same current as the power source

  1. Electric potential and e.m.f

(a) are the same terms                                            (b) are the different terms                                                              (c) have different units                                           (d) both (b) and (c)

  1. When we double the voltage in a simple electric circuit, we double the

(a) current   (b) power   (c) resistance        (d) both (a) and (b)

vii. If we double both the current and the voltage in a circuit while keeping its resistance constant, the power

(a) remains unchanged (b) halves      (c) doubles          (d) quadruples

viii. What is the power rating of a lamp connected to a 12 V source when it carries 2.5 A?

(a) 4.8 W  (b) 14.5 W   (c) 30 W      (d) 60 W

  1. The combined resistance of two identical resistors, connected in series is 8 . Their combined resistance in a parallel arrangement will be

(a) 2       (b) 4   (c) 8        (d) 12




  1. Define and explain the term electric current.
  2. What is the difference between electronic current and conventional current???
  3. What do we mean by the term e.m.f? ls it really a force? Explain.
  4. How can we differentiate between e.m.f. and potential difference?
  5. Explain Ohm’s law. What are its limitations?
  6. Define resistance and its units.
  7. What is the difference between conductors and insulators?
  8. Explain the energy dissipation in a resistance. What is Joule’s law?
  9. What is difference between D.C and A.C?
  10. Discuss the main features of parallel combination of resistors.
  11. Determine the equivalent resistance of series combination of resistors.
  12. Describe briefly the hazards of household electricity.
  13. Describe four safety measures that should be taken in connection with the household circuit.
  14. Design a circuit diagram for a study room that needs the following equipments in parallel: (a) One 100 W lamp operated by one switch. (b) One reading lamp fitted with a 40  bulb which can be switched ON and OFF from two points.  (c)  What is the advantage of connecting the equipment in parallel instead of series?


  1. Why in conductors charge is transferred by free electrons rather than by positive charges?
  2. What is the difference between a cell and a battery?
  3. Can current flow in a circuit without potential difference?
  4. Two points on an object are at different electric potentials. Does charge necessarily flow between them?
  5. In order to measure current in a circuit why ammeter is always connected in series?
  6. In order to measure voltage in a circuit voltmeter is always connected in parallel. Discuss.
  7. How many watt-hours are there in 1000 joules?
  8. From your experience in watching cars on the roads at night, are automobile headlamps connected in series or in parallel.
  9. A certain flash-light can use a 10 ohm bulb or a 5 ohm bulb. Which bulb should be used to get the brighter light? Which bulb will discharge the battery first?
  10. It is impracticable to connect an electric bulb and an electric heater in series. Why?
  11. Does a fuse in a circuit control the potential difference or the current?







  1. A current of 3 mA is flowing through a wire for 1 minute. What is the charge flowing through the wire? Ans: 180×10-3 C
  2. At 100,000 Ώ, how much current flows through your body if you touch the terminals of a 12 V battery? If your skin is wet, so that your resistance is only 1000 Ώ, how much current would you receive from the same battery? Ans:1.2×10-4A ,1.2×10-2 A
  3. The resistance of a conductor wire is 10 M Ώ. If a potential difference of 100 volts is applied across its ends, then find the value of current passing through it in mA. Ans. ( 0.01 mA)
  4. By applying a potential difference of 10 V across a conductor, a current of 1.5 A passes through it. How much energy would be obtained from the current in 2 minutes? Ans.(18O0J)
  5. Two resistances of 2 kΩ and 8 k Ω are joined in series, if a 10 V battery is connected across the ends of this combination, find the following quantities: (a) The equivalent resistance of the series combination.                                                                           (b) Current passing through each of the resistances.                                                   (c) The potential difference across each resistance. Ans. [(1) 10kΩ (b)1mA (c)2V,8V)
  6. Two resistances of 6 k Ω and 12 k Ω are connected in parallel. A 6 V battery is connected across its ends, find the values of the following quantities: (a) Equivalent resistance of the parallel combination.                                            (b) Current passing through each of the resistances.                                      (c)Potential difference across each of the resistance.  Ans: (a) 4kΩ, (b) 1mA, 0.5mA,(c) 6 V
  7. An electric bulb is marked with 220 V, 100 W. Find the resistance of the filament of the bulb. If the bulb is used 5 hours daily, find the energy in kilowatt-hour consumed by the bulb in one month (30days).Ans: 484Ω, 15kWh)
  8. An incandescent light bulb with an operating resistance of 95Ω is labeled “150 W.” Is this bulb designed for use in a 120V circuit or a 220 V circuit? Ans. (It has been designed for 120 V)
  9. A house is installed with
    • 10 bulbs of 60 W each of which are used 5 hours daily.
    • 4fansof75Weach of which run 10 hours daily.
    • One T.V. of 100Wwhich is used for5 hours daily. V
    • One electric iron of 1000 W which is used for 2 hours daily. lf the cost of one unit of electricity is Rs.4. Find the monthly expenditure of electricity (one month =30 days). Ans. (Rs- 1020)
  10. A 100 W lamp bulb and a 4 kW water heater are connected to a 250 V supply. Calculate(a) the current which flows in each appliance (b) the resistance of each appliance when in use. Ans. [(a) 0.4 A, 16A (b) 625 Ω, 15.62 Ω]
  11. A resistor of resistance 5.6 Q is connected across a battery of 3.0 V by means of a wire of negligible resistance. A current of 0.5 A passes through the resistor. Calculate                                                                                           (a) Power dissipated in the resistor.                                                                            (b)Total power produced by the battery.                                                                   (c)Give the reason of difference between these two quantities.                  [(a)1.4W (b)1.5W (c) some power is lost by the internal resistance of the battery.





































  1. Which statement is true about the magnetic poles?

(a) unlike poles repel                                       (b) like poles attract                                                       (c)magnetic poles do not effect each other(d)a single magnetic pole does not exist

  1. What is the direction of the magnetic field line§ inside a bar magnet?

(a) from north pole to south pole                  (b) from south pole to north pole                  (c) from side to side                                         (d) there are no magnetic field lines

iii. The presence of a/magnetic field can be detected by a

(a) small mass                                                                  (b) stationary positive charge                                 (c) stationary negative charge                                      (d) magnetic compass

  1. If the current in a wire which is placed perpendicular to a magnetic field increases, the force on the wire

(a) increases    (b) decreases  (c) remains the same  (d) will be zero

  1. A D.C motor converts

(a) mechanical energy into electrical energy                                                                    (b) mechanical energy into chemical energy                                                                                (c) electrical energy into mechanical energy                                                                                        (d) electrical energy into chemical energy

  1. Which part of a D.C motor reverses the direction of current through the coil every half-cycle?

(a)the armature    (b) the commutator  (c) the brushes          (d) r the slip rings

vii. The direction of induced e.m.f. in a circuit is in accordance with conservation of

(a) Mass     (b) charge    (c)momentum          (d) energy

viii. The step-up transformer

(a)increases the input current                          (b) increases the input voltage                               (c)has more turns in the primary                     (d)has less turns in the secondary coil

  1. The turn ratios of a transformer is 10. It means

(a)IS=10 IS     (b)NS=NP /10           (c)NS=10NP         (d)VS=VP /10


  1. Demonstrate by an experiment that a magnetic field is produced around a straight current-carrying conductor.
  2. State and explain the rule by which the direction of the lines of force of the magnetic field around a current carrying conductor can be determined;
  3. You are given an unmarked magnetized steel bar and bar magnet, its north and south ends are marked N and S respectively. State how would you determine the polarity at each end of the unmarked bar?
  4. When a straight current-carrying conductor is placed in a magnetic field, it experiences a force. State the rule by which the direction of this force can be found out.
  5. State that a current-carrying coil in a magnetic field experiences a torque.
  6. What is an electric motor? Explain the working principle of D.C motor.
  7. Describe a simple experiment to demonstrate that a changing magnetic field can induce e.m.f. in a circuit.
  8. What are the factors which affect the magnitude of the e.m.f. induced in a circuit by a changing magnetic field?
  9. Describe the direction of an induced e.m.f. in a circuit? How does this phenomenon relate to conservation of energy?
  10. Draw a labelled diagram to illustrate the structure and working of A.C generator.
  11. What do you understand by the term mutual induction?
  12. What is a transformer? Explain the working of a transformer in connection with mutual induction.
  13. The voltage chosen for the transmission of electrical power over large distances is many times greater than the voltage of the domestic supply. State two reasons why electrical power is transmitted at high voltage.
  14. Why is the voltage used for the domestic supply much lower than the voltage at which the power is transmitted?


  1. Suppose someone handed you three similar iron bars and told you one was not magnet, But the other two were. How would you find the iron bar that was not magnet?
  2. Suppose you have a coil of wire and a bar magnet. Describe how you could use them to generate an electric current.
  3. Which device is used for converting electrical energy into mechanical energy?
  4. Suppose we hang a loop of wire so that it can swing easily. If we now put a magnet into the coil, the coil will start swinging. Which waywill it swing relative to the magnet, and why?
  5. A conductor wire generates a voltage while moving through a magnetic field. In what direction should the wire be moved, relative to the field to generate the maximum voltage?
  6. What is the difference between a generator and a motor?
  7. What reverses the direction of electric current in the armature coil of D.C motor?
  8. A wire lying perpendicular to an external magnetic field carries W a current in the direction shown in the diagram below. ln what direction will the wire move due to the resulting magnetic force?


  1. A transformer is needed to convert a mains 240 V supply into a 12 V supply. Lf there are 2000 turns on the primary coil, then find the number of turns on the secondary coil. (100)
  2. A step-up transformer has a turn ratios of 1 : 100. An alternating supply of 20 V is connected across the primary coil. What is the secondary voltage? Ans. (2000 V)
  3. A step-down transformer has a turns ratio of 100 : 1. An ac voltage of amplitude 170 V is applied to the primary. If the current in the primary is 1.0 mA, what is the current in the secondary? Ans. (0.1A)
  4. A transformer, designed to convert the voltage from 240 V mains to 12 V, has 4000 turns on the primary coil. How many turns should be on the secondary coil? If the transformer were 100% efficient, what current would flow through the primary coil when the current in the secondary coil was 0.4 A? Ans. (200, 0.02A)
  5. A power station generates 500 MW of electrical power which is fed to a transmission line. What current would flow in the transmission line, if the input voltage is 250 kV? Ans. (2x 103 A)

























(i) The process by which electrons are emitted by e hot metal surface is known  as

(a) boiling     (b) evaporation     (c) conduction     (d) thermionic emission

  1. The Particles emitted from a hot cathode surface fare by

(a) positive ions    (b)  negative ions   (c) protons     (d) elections

iii. The logical operations performed by ma; gate is

(a) AND      (b) NOR      (c) NAND        (d)  OR

  1. AND gate pan be formed by using two

(a) NOT gates   (b) OR gates   (c) NOR gates          (d) NAND gates

  1. The output of a two-input NOR gate is 1 when:

(a) A is ‘1’ and B is ‘O’                                                     (b) A is ‘0’ and B is ‘1’                                                                                                       (c) both A and B are ‘0’                                           (d) both A and B are ’1’

  1. If X = A.B, then X is ‘1’ when:

(a) A and B are ‘1‘                                                         (b) A or B is ‘0’ ‘                                                         (c) A is ‘0’ and B is ‘1’ B                                              (d) A is ’1′ and B is ‘0’

vii. The output of a NAND gate is ‘0’ when

(a) i both of its inputs are ‘O’                                    (b) both of its inputs are ‘1                                      (c) anyi0fitsinputsis’0″                                             (d) any of its inputs is ‘1’



  1. Describe, using one simple diagram in each case, what happens when a narrow beam of electrons is passed through (a) a uniform electric field (b) a uniform magnetic field. What do these results indicate about the charge on electron?
  2. Explain the working of different parts of oscilloscope.
  3. Name some uses of oscilloscope.
  4. Considering an oscilloscope explain:                                   (i) How the filament is heated?                                                                                          (ii) Why the filament is heated?                                                                                   (iii) Why the anode potential is kept positive with respect to the cathode potential?                                                                                                                                                (iv) Why a large potential is applied between anode and cathode?              (v) Why the tube is evacuated?
  5. What is electron gun? Describe the process of thermionic emission.
  6. What do you understand by digital a find analogue quantities?
  7. Differentiate between analogue electronics and ‘digital electronics. Write down names of five analogue‘ and five digital devices that are commonly used in everyday life.
  8. State and explain for each case whether the information given by the following devices is in analogue or a digital form. (a) a moving-coil voltmeter measuring the e.m.f of at cell.                                                 (b) a microphone generating an electric current.                                                                  (c) a central heating thermostat controlling the water pump.                                       (d) automatic traffic lights controlling the flow of traffic.
  9. Write down some benefits of using digital electronics over analogue electronics.
  10. What are the three universal Logic Gates? Give their symbols and truth tables.






































  1. In computer terminology, information means

(a) any data    (b) raw data  (c) processed data    (d) large data

  1. Which is the most suitable means of reliable continuous communication between an orbiting satellite and Earth?

(a) micro waves   (b) radio waves  (c)  sound waves   (d) any light wave

iii. The basic operations performed by a computer are

(a) arithmetic operations                                      (b) non-arithmetic operations                                  (c) s logical operations                                         (d) both (a) and (c)

  1. The brain of any computer system is

(a) monitor   (b)memory   (c) CPU          (d) control unit

  1. Which of the following is not processing?

(a) arranging    (b) manipulating  (c) calculating        (d) gathering

  1. From which of the following-we can get information almost about everything

(a) book      (b) teacher   (c)computer         (d) H internet

vii. What does the term e-mail stand for?

(a)emergency mail   (b) electronic mail   (c) extra mail              (d) external mail


  1. What is difference between data and information?
  2. What do you understand by information and Communication Technology (ICT)?
  3. What are the components of information technology? Clearly indicate the function of each component.
  4. Differentiate between the primary memory and the secondary memory.
  5. Name different information storage devices and describe their uses.
  6. Explain briefly the transmission of radio waves through space.
  7. How light signals are sent through optical fibre?
  8. What is computer? What is the role of computer in everyday life?
  9. What is the difference between hardware and software? Name different soft wares.
  10. What do you understand by the term word processing and data managing?
  11. What is Internet? internet is a useful source of knowledge and information. Discuss.
  12. Discuss the role of information technology in school education.
  13. Why optical fibre is more useful tool for the communication process.
  14. Which is more reliable floppy disk or a hard disk?
  15. What is the difference between RAM and ROM memories?


18 TECHNOLOGY 174-192




  1. isotopes are atoms of same element with different

(a) atomic mass(b) atomic number   (c) number of protons(d) number of electrons

  1. One of the isotopes of uranium is : U. The number of neutrons in this isotope is

(a) 92 (b) 146  (c)238        (d)330

iii. Which among the following radiations has more penetrating power?

(a) a beta particle                                                  (b) a gamma ray                                                 (c) an alpha particle                                 (d) all have the same penetrating ability

  1. What happens to the atomic number of an element which emits one alpha particle?

(a) increases by 1   (b) stays the same  (c) decreases by 2      (d) decreases by 1

  1. The half-life of a certain isotope is 1 day. What is the quantity of the isotope after 2 days?

(a) one-half    (b) one-quarter  (c) one-eighth    (d) none of these

  1. When Uranium (92 protons) ejects a beta particle, how many protons will be in the remaining nucleus?

(a) 89 protons          (b ) 90 protons    (c) 91 protons           (d) 93 protons

Release of energy by the Sun is due to

(a) nuclear fission (b) nuclear fusion (c) burning of gases (d) chemical reaction

vii. When a heavy nucleus splits into two lighter nuclei, the process would

(a) release nuclear energy                                                  (b) absorb nuclear energy                                (c) release chemical energy                                              (d) absorb chemical energy

  1. The reason carbon-dating works is that

(a) plants and animals are such strong emitters of carbon-14                                            (b) after a plant or animal dies, it stops taking in fresh carbon-121                                (c) there is so much non-radioactive carbon dioxide in the air                                                                                (d) when plants or animals die, they absorb fresh carbon-14



  1. What is difference between atomic number and atomic mass number? Give a symbolical representation of a nuclide.
  2. What do you mean by the term radioactivity? Why some elements are radioactive but some are not?
  3. How can we make radioactive elements artificially? Describe with a suitable example.
  4. What are the three basic radioactive decay processes and how do they differ from each other?
  5. Write the alpha decay process for Identify the parent and daughter nuclei in this decay.
  6. Explain whether the atomic number can increase during nuclear decay. Support your answer with an example.
  7. What do you understand by half-life of a radioactive element?
  8. ls radioactivity a spontaneous process? Elaborate your answer with a simple experiment.
  9. What is meant by background radiations? Enlist some sources of background radiations.
  10. Describe two uses of radioisotopes in medicine, industry or research.
  11. What are two common radiation hazards? Briefly describe the precautions that are taken against them.
  12. Complete this nuclear reaction: Uà X +2 01 Does this reaction involve fission or fusion? Justify your answer.
  13. Nuclear fusion reaction is more reliable and sustainable source of energy than nuclear fission chain reaction. Justify this statement with plausible arguments.
  14. A nitrogen nuclide 11°N decays to become an oxygen nuclide by emitting an electron. Show this process with an equation.
  15. Determine which of these radioactive decay processes are possible. (a)  Po à      Po + He                                                                                     (b) Th à  Ra + He                                                                                           (c) Pa à U + β                                                                                               (d)   C +à N + β


  1. ls it possible for an element to have different types of atoms? Explain.
  2. What nuclear reaction would release more energy, the fission reaction or the fusion reaction? Explain.
  3. Which has more penetrating power, an alpha particles or a gamma ray photon?
  4. What is the difference between natural and artificial radioactivity?
  5. How long would you likely have to wait to watch any sample of radioactive atoms completely decay?
  6. Which type of natural radioactivity leaves the number of protons and the number of neutrons in the nucleus unchanged?
  7. How much of a 1g sample of pure radioactive substance would be left undecayed after four half-lives?
  8. Tritium, H is radioactive isotope of hydrogen. lt decays by emitting an electron. What is the daughter nucleus?
  9. What information about the structure of the nitrogen atom can be obtained from its nuclide N ? ln what way atom in N is different from the atom in N ?



  1. The half-life of N is 7.3 s. A sample of this nuclide of nitrogen is observed for 29.2 s. Calculate the fraction of the original radioactive isotope remaining after this time. Ans. (1/16)
  2. Cobalt-60 is a radioactive element with half-life ofi5.25 years. What fraction of the original sample will be left after 26 years? Ans.(1/32)
  3. Carbon-14 has a half-life of S730 years. How long will it take for the quantity of carbon -14 in a sample to drop to one-eighth of the initial quantity? Ans. (1.72 X 104 years)
  4. Technetium-99 m is a radioactive element and is used to diagnose brain, thyroid, liver and kidney diseases. This element has half-life of 6 hours. If there is 200 mg of this technetium present, how much will be left in 36 hours. Ans.(3.12 mg)
  5. Half-life of a radioactive element is 10 minutes. If the initial count rate is 368 counts per minute, find the time for which count rate reaches 23 counts per minute. Ans. (40 minutes)
  6. In an experiment to measure the half-life of a radioactive element, the following results were obtained:

Count rate/minute 400 ‘2O0 100 50 25                                                                                      Time(in minutes)        0       2      4   6   8

Plot a graph between the count rate and time in minutes. Measure the value for the half-life of the element from the graph. Ans. (half-life is 2 minutes)

  1. A sample of certain radioactive element has a half-life of 1500 years. elf it has an activity of 32000 counts per hour at the present time, then plot a graph of the activity of this sample over the period in which it will reduce to 1/16 of its present value.
  2. Half-life of a radioactive element was found to be 4000 years. The count rates per minute for 8 successive hours were found to be 270, 280, 300, 310, 285, 290, 305,
  3. What does the variation in count rates show? Plot a graph between the count rates and time in hours. Why the graph is a straight line rather than an exponential? Ans. (Variation in count rate shows the random nature of radiactive decay, graph is almost horizontal line rather than exponential curve which is due to long half-life as compared to period of 8,hours)
  4. Ashes from a campfire deep in” a cave show carbon-14 activity of only one-eighth the activity of fresh wood. How long ago was that campfire made? Ans. (17190 years)
  GLOSSARY 193-197



  • AMMETER: An instrument which measures larger current.
  • AMPERE: If one coulomb of charge passes through any cross section in one second, then current will be equal to one ampere.
  • AMPLITUDE: The maximum displacement below or above the mean position of a vibrating body.
  • ANALOGUE ELECTRONICS: The branch of electronics which processes in the form of analogue quantities.
  • ANALOGUE QUANTITIES: Those quantities which change continuously with time or remain constant.
  • APERTURE: The line joining the end points of a spherical mirror.
  • ATOMIC MASS NUMBER: The sum of neutrons and protons present in a nucleus.
  • BOOLEAN ALGEBRA: The branch of mathematics which deals with the relationships of logic variables.
  • BOOLEAN VARIABLES: Such things which have only two possible states.
  • CAPACITANCE: The ability of the capacitor to store charge.
  • CAPACITOR: A device used to store electric charge.
  • CAPACITORS IN SERIES: ln this combination, the capacitors are connected side by side.
  • CATHODE-RAY OSCILLOSCOPE: An instrument be used to display the magnitudes of rapidly changing electric current or potential as a function of time.
  • CATHODE-RAY TUBE: A vacuum tube used to accelerate electrons which emit from the cathode by applying high voltage between cathode and anode.
  • CENTRELOF CURVATURE: The centre of the hollow sphere of which a spherical mirror is a part.
  • ATOMIC Number: The number of protons present in a nucleus.
  • CLADDING: The inner part of the fibre optics.
  • COMMUNICATION TECHNOLOGY: An electronic based a system of information transmission, reception, processing and retrieval.
  • COMPACT DISC: A molded plastic disc containing digital data that is scanned by a laser beam for the reproduction of recorded sound or other information.
  • COMPOUND MICROSCOPE: A light microscope used to investigate small objects.
  • COMPRESSIONAL WAVES: The longitudinal waves comprising series of compressions and rarefactions.
  • COMPUTER: An electronic device used to perform mathematical and logical operations at high speed.
  • CONCAVE MIRROR: A spherical mirror whose inner curved surface is reflecting.
  • CONVEX MIRROR: A spherical mirror whose outer curved surface is reflecting;
  • CONVEX LENS: A lens that causes incident parallel rays to converge at the focal point.
  • CONCAVE LENS: A Lens which diverges the parallel rays of light from its surface.
  • COULOMB’S LAW: The force of attraction or repulsion between two charged bodies is directly proportional to the ‘product of the quantity of charges and inversely proportional
  • to the square of the distance between them.
  • CRESTS AND TROUGHS: In transverse waves, the highest points and the lowest points of the particles of the medium from the mean position.
  • CYCLE: One complete vibration of a wave.
  • DATA MANAGING: To collect information for a special purpose and to store it in a computer in a file form.
  • DATA: Facts and figures that are used by programs to produce useful information.
  • DIFFRACTION OF WAVES: The bending of waves around obstacles or sharp edges.
  • DIGITAL ELECTRONICS: The branch of electronics -which processes data in the form of digits.
  • DIGITAL QUANTITIES: The quantities which change in non continuous steps.
  • ELECTRIC CURRENT: The time rate off low of electric charge through any cross section.
  • ELECTRIC POTENTIAL: The amount of work done in bringing a unit positive charge from infinity to a particular point in an electric field.
  • ELECTRIC POWER: The amount of energy supplied by current in a unit time.
  • ELECTROMAGNET: The type of magnet which is created when current flows through a coil.
  • ELECTROMAGNETIC INDUCTION: The production of an electric current across a conductor moving through a magnetic field.
  • ELECTRON VOLT: The kinetic energy that an electron gains when accelerated between two points with a potential difference of-1 V. 1eV= 1.6 x 10-19
  • ELECTRONICS: The branch of applied physics which discusses those principles and ways by means of which we control the flow of electrons using different devices.
  • ELECTROSTATIC INDUCTION: In the presence of a charged body, an insulated conductor having positive charges at one end and negative charges at the other end.
  • EMF: The total amount of energy supplied by the battery or the cell in moving one coulomb of positive charge from the positive to the negative terminal of the battery.
  • EN DOSCOPE: A medical instrument used for exploratory, diagnostic, and surgical purposes.
  • FARSIGHTEDNESS (HYPERMETROPIA): The disability of the eye to form distinct images of nearby objects on its retina.
  • FAX MACHINE: A mean to send the documents from one place to another through telephone lines.
  • RIGHT HAND RULE: Grasp a length of wire with your right hand such that your thumb points in the direction of the current. Then fingers of your right hand circling the wire will point in the direction of the magnetic field.
  • FISSION REACTION: The process of splitting up a heavy nucleus into two smaller nuclei with release of large amount energy.
  • FLASH DRIVE: A small storage device that can be used to -transport files from one computer to another.
  • FLEMING’S LEFT HAND RULE: Stretch the thumb, forefinger and the middle finger of the left hand are mutually perpendicular to each other. If the forefinger points in the direction of the magnetic field, the middle finger in the direction of the current, then the thumb.
  • OHM’S LAW: The current passing through a conductor is directly proportional to the potential difference applied across its ends, provided the temperature and physical state of the conductor do not change.
  • OPTICAL CENTRE:’A point on the principal axis at the centre of a lens.
  • PARALLEL CIRCUIT: A circuit in which voltage remains the same across each resistor.
  • PERIODIC MOTION: The regular motion of a body which repeats itself in equal intervals of time.
  • PITCH: The characteristics of sound by which a shrill sound can be distinguished from a grave one.
  • POLE: The mid-point of the aperture of the spherical mirror.
  • POWER OFACCOMMODATION: The ability of the eye to change the focal length of its lens so as to form clear image of an object on its retina.
  • PRINCIPAL AXIS: The straight line passing through the pole and the centre of curvature of a spherical mirror.
  • PRINCIPAL FOCUS: A point on the principal axis of [mirror/lens where a beam of light parallel to the principal axis converges to or appears to diverge after reflection from the spherical mirror/lens.
  • PRISM: A transparent triangular piece of glass with at least two polished plane faces inclined towards each other from which light is reflected’ or refracted.
  • QUALITY OF SOUND: The characteristics of sound by which two sound waves of same loudness and pitch are distinguished from each other.
  • RADIOACTIVITY: A phenomenon in which radioactive element emits radioactive rays.
  • RADIUS OF CURVATURE: The radius of the hollow sphere of which a spherical mirror is a part.
  • REFLECTION OF LIGHT: When light travelling in a certain medium falls on the surface of another medium, a part of it returns back in the same medium.
  • REFRACTION: The change of path of waves/light while passing from one medium into another medium due to change in speed.
  • REFRACTIVE INDEX: The ratio of the speed of light in air to the speed of light in a material:
  • RESISTANCE: The measure of opposition to the flow of current through a conductor.
  • RIPPLE TANK: A device used to produce and manipulate water waves.
  • H.M: To and fro oscillatory motion in which acceleration of the body is directly
  • proportional to the displacement of the body from the mean position and is always directed towards the mean position.
  • SERIES CIRCUIT: A circuit in which current remains the same across each resistor.
  • SIMPLE MICROSCOPE: A convex lens of short focal length which is used to produce magnified images of small objects.
  • SOFTWARE: It refers to computer programs and the manuals that support them.
  • SOLENOID: A coil of wire consisting of many loops.
  • SOUND: A form of energy that is passed from one point to another in the form of waves.
  • SPHERICAL MIRROR: A mirror whose polished, reflecting surface is a part of a hollow sphere of glass or plastic.
  • THERMlONlC EMISSION: The process of emitting of electrons from hot cathode.
  • TRANSFORMER: An electrical device which is used to increase or decrease the value of an alternating voltage.
  • TRANSVERSE WAVES: The mechanical waves in which particles of the medium vibrate about their mean position perpendicular to the direction of propagation of the waves.
  • TRUTH TABLES: The truth tables are tables which give the values of the inputs and outputs of the basic types of logic gates or combination of such gates.
  • ULTRASONICS: Sound waves of frequency higher than 20, O00 Hz.
  • WAVE: A disturbance in a medium which travels from one place to another.
  • WAVELENGTH: The distance between two consecutive crests or troughs.
  • WORD PROCESSING; Such a use of computer through which we can write a letter, prepare reports and books, etc.


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