🌊PAPER 06-QNS

 

FORM FOUR PHYSICS BANK OF QUESTIONS

1. WAVES

1.1. Introduction to Waves

1. Define the following terms:

1. Wave

2. Wavelength

3. Period

4. Frequency

5. Amplitude

6. Crest

7. Trough

8. Wave velocity

2. Explain two (2) types of waves.

3. Explain the relationship between wave, wavelength, velocity, period and frequency.

4. From the diagram below, determine the amplitude, period and frequency of the wave.

5. From the diagram below, determine the wavelength and velocity of the wave, frequency of the wave is 5Hz.

6. What is the amplitude and wave length of the wave in the diagram below?

7. A periodic and repeating disturbance in a lake creates waves which emanate outward from its source to produce circular wave patterns. If the frequency of the source is 2.00 Hz and the wave speed is 5.00m/s, calculate the wavelength.

8. Calculate the wavelength of red light in air if the frequency of red light is 4.3 × 10¹⁴ Hz, C = 3.0 × 10⁸.

9. A pendulum makes exactly 40 vibrations in 20.0 s. Calculate its period.

10. What would be the wavelength if the frequency of a wave is doubled and its speed remains constant?

11. A wave whose speed in a snake is 4.4 m/s enters a second snake. The wavelength changes from 2.0 m to 3.0 m. The wave in the second snake travels at approximately ____.

12. A 2.0-meter long rope is hanging vertically from the ceiling and attached to a vibrator. A single pulse is observed to travel to the end of the rope in 0.50 s. What frequency should be used by the vibrator to maintain three whole waves in the rope?

13. Transverse stationary waves are set up in a long string using a suitable vibrator of frequency 60 Hz. The average distance between successive nodal points is measured to be 50 cm .Calculate the velocity of transverse waves in the string.

14. The distance between successive crests of water ripples in a ripple tank experiment is 3.2 cm and their wave speed is 26 cm/s. Determine the wavelength, frequency and period of the ripples.

15. A periodic disturbance in a lake creates waves which emanate outwards from its source to produce circular wave patterns. If the frequency of the source is 2 Hz and wave speed is m/s, determine the distance between adjacent wave crests.

16. For a certain transverse wave, the distance between two successive crests is 1.1 m, and eight crests pass a given point along the direction of travel every 12 s. Calculate wave speed.

17. A sinusoidal wave is travelling along a rope. The oscillator that generates the wave completes 40 vibrations in 30s. Also, a given crest of the wave travels 425 cm along the rope in 10 s. Calculate the wavelength of the sinusoidal wave.

18. A straight vibrator causes water ripples to travel across the surface of a shallow tank. The ripples travel a distance 33 cm in 1.5 s and the distance between successive crests of the wave is 4.0 cm. Calculate the frequency of the vibrator

19. Water ripples are caused to travel across the surface of a shallow tank by means of a suitable straight vibrator. The distance between successive crests and troughs is 1.5 cm and the wave travels 25.2 cm in 1 s. Calculate the wavelength, the velocity of the waves and the frequency of the vibrator.

20. If a wave has a velocity of 340 m/s and a wavelength of 0.5 m, calculate the frequency of the vibrator.

21. If the frequency of radio waves is 600 kHz, find the wavelength of the waves. The speed of radio waves = 3 x 10⁸ m/s.

22. Calculate the velocity of the wave whose wavelength is 1. 7 x10^-2 m and frequency 2x10¹⁴ Hz.

23. The radio waves have a velocity of about 3.0 x10⁸ m/s and the wavelength of 1500 m. Calculate the frequency of these waves.

24. Consider the figure below illustrates part of a wave traveling across the water at a particular place, Calculate;

    1. The frequency of the wave.

    2. The wavelength of the wave.

    3. The amplitude of the wave.

    4. The velocity

1. The wavelength of signals from a radio transmitter is 1500m and the frequency is the 200 KHz. To what speed does the radio wave travel? What is the wavelength of a transmitter operating at 1000 KHz?

2. A certain wave has a periodic time of 0.04 second and travels at 30 x 10⁷ m/s. Find its wavelength.

3. The commercial Programme of radio Tanzania is broadcast on wavelengths of 1500m and 247 m. The frequency of the 1500 m wave is 200 kHz. What is (a) The velocity of the wave?

(b) The frequency of the 247 m wave?

1.2. Behaviour of Waves

1. Describe four (4) properties of a wave.

2. Explain applications of;

1. Reflection of waves

2. Refraction of waves

3. Diffraction of waves

4. Interference of waves

3. The speed of light is 2.25 × 10⁸ m/s in water and 3 × 10⁸ m/s in air. Determine: (a) The refractive index of light from air to water.

(b) The angle of refraction in the water if the incident angle of light at the surface of water is 30°.

4. State the principle of superposition of waves.

5. Distinguish between constructive from destructive interference.

6. Explain how:

   1. A bat is able to travel in caves even during the dark night.

   2. To distinguish pure diamond from other ores.

   3. Noise is reduced in ear pods.

   4. Signal can be transferred even through obstacles.

7. If you want to hit fish under water using a spear, should you aim below it straight it or above it? Explain.

8. A wave whose speed in first medium is 4.4 m/s enters a second medium. The wavelength changes from 2 m to 3 m. What is the speed of the wave in second medium?

9. Two sets of transverse waves arrive at the same time. Under what conditions do they: (i) Cancel out

(ii) Produce a larger wave

10. Radio and light waves travel at a velocity of 3 × 10⁸ m/s in air. Calculate:

1. The wavelength of radio waves when transmitted at a frequency of 150 MHz,

2. The velocity of light in glass of refractive index, η of 1.5.

11. Give reasons for the following:

    1. During the day sound from distant sources are not very clear unlike during the night.

    2. The amplitude of the wave does not change as it crosses the boundary.

1.3. Propagation of Waves

1. Explain two types of mechanical waves and their propagations

2. Define the following terms:

   1. Longitudinal waves

   2. Transverse waves

   3. Compressions

   4. Rarefactions (v) Electromagnetic waves

3. Describe the characteristics of: (a) Mechanical waves

(b) Longitudinal waves

4. Describe properties of mechanical waves.

1.4. Sound Waves

1. Define the following terms:

1. Sound

2. Echo

3. Reverberation

2. Explain the concept of audibility range.

3. Explain the mechanism of hearing.

4. Draw a well labeled diagram of human ear and describe its structure.

5. Sound of explosions taking place on other planets is not heard by a person on the Earth. Explain.

6. A sonar device on a submarine sends out a signal and receives an echo 6 s later. Calculate the speed of the sound in water if the distance of the object from the submarine is 3769 m.

7. A person standing 99 m from the foot of tall building claps hands and hears an echo

0.5 s later. Calculate the speed of sound in air.

8. An observer stands between two distant cliffs and claps hands. An echo is received after 2 s and 2.5 s respectively. If the speed of sound in air is 330 m/s, find the distance between cliffs.

9. How long would it take for a 25 Hz beat to reach an audience member 100m away when the ambient temperature is 21 ℃?

10. Calculate the ratio of velocities of sound produces in dry air at 42 ℃ to another at 60

℃.

11. Two persons stand facing each other, 220 m apart on one side of a high wall and at the same perpendicular distance to it. When one fires a pistol the other hears a report 0.7 s after the flash and a second 0.25 s after the first. Explain this and calculate:

1. The velocity of sound in air.

2. The perpendicular distance of the persons from the wall.

3. Draw a diagram showing the positions of the persons and the wall.

12. Describe the factors affecting the speed of sound in air.

13. Explain briefly why sound produced in hall with many people is heard more clearly than when the hall has few people.

14. A person standing 99m from the foot of mountains claps his hands and hears an echo

0.6 second later. Calculate the speed of the sound in the air.

15. An echo sounder produces a pulse and an echo is received from the sea – bed after 0.4 seconds. If the speed of sound in water is 1500 m/s, calculate the depth of the sea –bed.

16. In determining the depth of an ocean an echo sounder produces ultrasonic sound. Give reasons why ultra sound is preferred for this purpose.

17. A gun was fired and the echo from a cliff was heard 8s later. How far was the gun from the cliff?

18. It is possible to hear sound round obstacles but not possible to see light. Give reason.

19. A fathometer produces sound in a ship and receives two echoes where there is a raised sea bed one after 2.5 seconds and the other after 3.0 seconds. Find the height of the raised sea bed (Take V in water = 1460 m/s).

20. A girl standing 200 m from the foot of a high wall claps her hands and the echo reaches her 1.16 seconds later. Calculate the velocity of sound in air using this observation.

21. From the figure below, give reason why, an observer moving along the line AB hears loud sound at same point and soft sound at other points. How is the sound along the line OC? (When he moves along line OC hears loud sound only).

22. A person stands 100 m from the foot of tall building claps his hands and hears an echo

0.588 seconds later .Calculate the velocity of sound in air.

23. The velocity of sound in air is 330 m/s; Find the wavelength in water of sound wave of frequency 660 Hz if the velocity of sound in water is 1. 32 km/s.

24. A source of sound produces waves of wavelength 0.8 m in air. The same source of sound produces waves of wavelength 4.0 m in air. If the velocity of sound in air is 332 m/s, find the velocity of sound in water.

25. How far does sound travel in air when a turning fork of frequency 250 Hz completes 50 vibrations? The speed of sound in air is 340 m/s.

26. A bat emits ultrasonic sound of frequency 100 kHz in air. If this sound meets a water surface, what is the wavelength of (i) the reflected sound (ii) the transmitted sound? If the speed of sound in air = 340m m/s and in water = 1486 m/s.

27. A stone is dropped into a well 19.6 m deep and the impact of sound is heard after

2.056 seconds. Find the velocity of sound in air.

28. A personal with deep voice singing a note of frequency 200Hz is producing sound waves whose velocity is 330m/s. find the sound's wave length.

29. A hospital uses an ultrasonic scanner to locate tumours in a tissue. What is the wavelength of sound in a tissue in which the speed of sound is 1.7 km/s? The operating frequency of the scanner is 4.2 MHz.

30. Find the wavelength of sound wave whose frequency is 550Hz and speed is 330m/s.

31. A signal is sent to the seabed from the bottom of a ship. The signal comes back in one – fifth of a second .How deep is the water?

32. Sound travels 1.7 Km in 5 seconds .The time between a flash of lightning and the thunder is 10 s. How far away is the storm?

33. A loud sound is made and the echo from a distant cliff is heard 8 s later .If the atmospheric temperature is 220 C; how far away is the cliff?

1.5. Musical Sound

1. Explain three (3) properties musical sounds.

2. Explain the factors affecting:

1. Loudness of musical sound.

2. Pitch of musical sound.

3. Quality of musical sound.

3. Define the following terms: (i) Musical sound

2. Musical instrument

3. Beat

4. Beat frequency

5. Stationary wave

6. Fundamental note

7. Sonometer

8. Forced vibrations

9. Resonance

10. Noise

11. Node

12. Antinode

4. Describe three (3) categories of musical instruments.

5. Explain factors affecting the frequency of vibrating string.

6. A string has a length of 75 cm and a mass of 8.2 g. The tension in the string is 18 N. What are the frequencies at the 1^st and 3^rd harmonics?

7. The vibrating length of a stretched wire is altered at constant tension until the wire oscillates in unison with a tuning fork of frequency 320 Hz. The length of the wire is again altered until it oscillates in unison with tuning fork of unknown frequency. If the two lengths are 90 cm and 65.5 cm, respectively, determine the unknown frequency.

8. The tuning fork of frequency 512 Hz is sounded at the mouth of a tube closed at one end with a movable piston. It is found that resonance occurs when the column of air is 18 cm long and again when the column is 51 cm long. Use this information to determine the velocity of sound in air.

9. In a closed pipe, the first resonance is at 23 cm and second at 73 cm. Determine the wavelength of the sound and the end correction of the pipe.

10. A tuning fork of frequency 250 Hz is used to produce resonance in an open pipe. Given that the velocity of sound in air is 350 m/s, find the length of the tube which gives:

(a) The first resonance. (b) Third resonance.

11. A 256 Hz tuning fork produces sound at the same time with a 249 Hz fork. What is the beat frequency?

12. A string of length 1.2 m is stretched and made to vibrate so that a stationary wave consisting of two loops is produced.

1. Draw a sketch of the wave.

2. Determine the wavelength of the wave

13. A wire of length 20 cm, mass 1.2 g and under a tension of 120 N is plucked to generate a wave. Determine:

1. The fundamental frequency

2. The frequency of the third harmonic

14. The fundamental frequency of vibration of a string is f. What will the fundamental frequency be if the length of the string is halved and the tension is increased four times?

15. A closed pipe has a fundamental frequency of 400 Hz. Calculate:

1. The frequency of the first overtone

2. The fundamental frequency of an open pipe of the same length. (Given that the speed of sound waves in air, v = 340 m/s).

16. A speaker delivering a note of frequency 250 Hz is placed over the upper end of a vertical tube filled with water. When the water is gradually run down the tube, the air column resonates when the water level is 31 cm below the top of the tube. The air column resonates again when the water level is 99.8 cm below the top of the tube.

Determine:

1. The speed of sound in air

2. The end correction

17. If the shortest length of a tube for resonance is 0.12 m and the next resonant length is

0.37 m, what is the frequency vibration? Take the speed of sound in air 340 m/s.

18. A column of air 26.25 cm long in a closed tube resonates to a sounding tuning fork. If the velocity of sound in air is 33600 cm/s, what is the frequency of the fork? Ignore end correction.

19. A Sonometer wire of length 40cm between two bridges produces a note of 512Hz when plucked at the midpoint. Calculate the length of the wire that would produce a note of 256Hz with the same tension.

20. A turning fork of frequency 512 Hz is sounded at the mouth of a tube closed at one end with a movable piston. It is found that resonance occurs when the column of air is 18cm long and again when the column is 51cm long. Find wave length and velocity of sound in air.

21. In a closed pipe, the first resonance is at 23cm and second at 73cm. determines the wave length of the sound and the end correction of pipe.

22. (a) Identify three characteristics of sound which distinguish one note from another. Hence state the physical factors which correspondingly define the mention characteristics

(b) A resonance tube whose one end is closed and other open, resonance to a note of frequency 560Hz when the length of the air column is 15cm. determine the wave length of this sound in air. What is the shortest length of the air column which resonates in similar conditions to a note of frequency 1000Hz?

23. A string has a length of 75cm and a mass of 8.2g, the tension in the string is 18N.Calculate the 1st harmonic and 3rd harmonic.

24. A string of length 1 m and mass 5 x 10-4 kg fixed at both ends is under a tension of 20 N. It is plucked at a point situated 25 cm from one end. What would be the frequency of vibrations of the string?

25. A wire of length 140 cm and mass 0.52 x 10-3 kg is stretched by means of a load of 16 kg. Calculate the frequency of the fundamental note.

26. The vibration length of a stretched wire is altered at constant tension until the wire oscillates in unison with a turning fork of frequency 320 Hz. The length of a wire is again altered until it oscillates in unison with a fork of unknown frequency. If the two lengths are 90 cm and 65.5 cm, respectively, determine the unknown frequency.

27. The length of a sonometer wire between two fixed ends is 110 cm. Where the two bridges should be placed so as to divide the wire into three segments whose fundamental frequencies are in the ratio 1:2:3?

28. A 90 cm long wire of a sitar has a fundamental frequency of 256Hz. At what distance from the upper end should the wire be compressed so that a note of frequency 384 Hz is produced?

29. A nylon string is stretched between supports 1.2 m apart. Given that the speed of sound in the string is 800 m/s, find the frequency of the fundamental vibration and the first two overtones.

30. A Sonometer wire of length 40cm between two bridges produces a note of 512Hz when plucked at the midpoint. Calculate the length of the wire that would produce a note of 256Hz with the same tension.

31. A sonometer wire of length 40 cm between two bridges produces a note of 512 Hz when plucked at the midpoint .Calculate the length of the wire that would produce a note of 256 Hz with the same tension.

32. The frequency obtained in a plucked string is 500Hz when the tension is 3 N .calculate

1. The frequency when the tension is increased to 10 N

2. The tension needed to produce a note of frequency 800 Hz

33. A plucked string of length 30 cm has a mass per unit length of 0.5 kg/m .If the tension in the string is equal to 40 N ,Find :

1. The fundamental frequency

2. The first overtone frequency

3. The second overtone frequency

34. A plucked wire of 10 m long and radius of 7mm has a density of 500 kg/m3. Calculate (i) The fundamental frequency

(ii) The first overtone frequency needed to produce a tension of 8 N

35. A string has a length of 75cm and a mass 0f 8.2g. The tension in the string is 18N. Calculate the velocity of the sound wave in the string.

36. Given that the velocity of the sound wave emitted from a string is 50m/s the Length of the string is 40cm and the mass of the string is 0.0004kg calculate the tension of the string.

37. A sonometer wire of length 50cm vibrate with frequency 384Hz. Calculate the length of the sonometer wire so that it vibrates with frequency of 512Hz.

38. A sonometer wire of length 40cm between two bridges produces a note of frequency 512Hz when plucked at midpoint. Calculate the length of the wire that would produce a note of frequency 256Hz with the some tension.

39. The frequency obtained from a plucked string is 400Hz when the tension is 2 Newton.

Calculate;

1. The frequency when the tension is increased to 8N

2. The tension needs to produce a note of frequency 600Hz

40. Given that the frequency obtained from a plucked string is 800Hz when the tension is 8N. Calculate;

1. The frequency when the tension is doubled

2. The tension required when the frequency is halved

41. Under constant tension the note produced by a plucked string is 300Hz when the length is 0.9m;

1. At what length is the frequency 200Hz?

2. What frequency is produce at 0.3m

42. A string fixed between two supports that are 60cm a part. The speed of a transverse wave in a string is 420m /s. Calculate the wavelength and the frequency for Fundamental note, Second overtone and Fifth overtone.

43. A string is fixed two ends 50cm a part. The velocity of a wave in a string is 600m/s.

Calculate;

1. The first five over tone

2. The tenth overtones

44. Given that the refractive index of glass is 1.52. The wavelength of the radio waves in vacuum is 1.5 x 103m .Calculate the wavelength of the radio waves in glass.

45. A guitar wire fixed between two supports 60cm a part produced wave of frequency 500Hz. Calculate;

1. The frequency of a wave when the length of the guitar wire is reduced to quarter

2. The length of the guitar wire when the frequency of the wave produced is 2000Hz

46. A string A is 2m long and has a linear mass density of 9 g/cm3. String B has a linear mass density of 18g/cm3 .If the tension in both strings is the same, how long must string B be for it to be raised to hear the next peak in intensity.

47. The vibrating length of a stretched wire is altered at constant tension until the wire oscillates in unison with a turning fork of frequency 320 Hz. The length of the wire is again altered until it oscillates in unison with a fork of unknown frequency. If the two lengths are 90 cm and 60 cm, respectively, determine the unknown frequency.

48. What is the approximate distance of a thunderstorm when you note a 3 s delay between the flash of lighting and the sound of thunder?

49. How long does it take for a radio signal sent from the earth to reach the moon? The distance from the earth to the moon is 3.84 x 10⁶ m

50. During a storm, thunder is heard 7 s after the lightning is seen .If the temperature of the air is 28 ℃, how far away is the storm.

51. In a resonance tube experiment, the smallest value of L for which a peak in sound intensity occurs is 9.0 cm .How much must the tube be raised to hear the next peak in intensity.

52. A helicopter is hovering at an altitude of 200 m above the surface of a lake. A speaker on the helicopter is sending out sound waves ,which are reflected from both the surface of the water and the bottom of the lake .If the difference in arrival times of the two echoes is measured to be 0.24 s, what is the depth of the lake ?(The atmospheric temperature is 20 ℃).

53. Matter expands when heated and contracts when cooled .Explain why a musician must re – tune a stringed instrument if its temperature changes.

54. Explain why it is not advisable for soldiers to march across a bridge in rhythm.

55. Guitars have strings of varying thickness .Which of the strings (thickest or thinnest) produces the highest frequency of musical notes? Explain your answer.

56. Give reasons for the following:

1. If a very loud sound is produced near the mouth of the glass bottle, the glass is likely to break.

2. Buildings are likely to collapse following the occurrences of the earth quake.

57. A resonance tube whose one end is closed and other open, resonance to a note of frequency 560Hz when the length of the air column is 15cm. determine the wave length of this sound in air. What is the shortest length of the air column which resonates in similar conditions to a note of frequency 1000 Hz?

58. Pipe closed at one end has a length of 100 cm. If the velocity of sound in air of the pipe is 340m/s. Calculate the frequency of;

1. The fundamental

2. The first overtone

59. A turning fork of frequency 256 Hz is sounded at the mouth of a tube closed at one end with a movable. It is found that resonance occurs when the column of air is 15 cm long and again when the column is 80 cm long. Determine the velocity of sound in air.

60. The speed of sound waves in air is found to be 340m/s. Find;

1. The fundamental frequency

2. The frequency of the 3rd harmonic (c) The frequency of 9th harmonic

(d) The frequency of 51st harmonic.

Given that the sound waves are probating in a closed pipe of length 700m.

61. In a closed pipe, the first resonance is at 23 cm and second at 73 cm. Determine the wavelength of the sound and the end correction of the pipe.

62. A pipe closed at one end has a length of 10cm. If the velocity of sound in the air of the pipe is 340m/s. Calculate the frequency of;

1. The fundamental

2. 1st overtone

63. When a tuning fork of 512Hz is sounded at the top of the measuring cylinder which contains water. The first resonances are observed when the length of the air column (the distance from the mouth to the level of the water is 50 cm) and the second resonance is observed when the length of the air column (the distance from the mouth to the level of water) is 80 cm; using these observations. Calculate the velocity of water in air.

64. A 256Hz turning fork produces sound at the same time with a 249Hz turning fork. What is the beat frequency?

65. What is the beat frequency when a 262 Hz and 266 Hz turning forks are sounded together?

1.6. Electromagnetic Spectrum

1. Define electromagnetic spectrum

2. Arrange the electromagnetic waves in order of:

   1. Increasing wavelength

   2. Increasing frequency

3. Describe properties of electromagnetic waves.

4. Explain applications of electromagnetic waves.

5. Explain how electromagnetic waves are produced.

6. Describe effects of electromagnetic waves.

2. ELECTROMAGNETISM

2.1. Magnetic Fields due to Current – carrying Conductor

1. Define the term electromagnetism.

2. Explain how to determine the direction of magnetic field produced by a current carrying conductor.

3. State:

   1. The Right hand grip rule

   2. Maxwell’s cork screw rule

   3. Fleming’s left hand rule

4. Explain methods of increasing magnetic field in a solenoid.

5. Give evidence of the existence of a magnetic field around a current carrying conductor.

6. Describe how you would use your right hand to determine the direction of a magnetic field around a current carrying conductor.

7. Write at least two applications of Maxwell’s cork screw rule.

8. In an experiment where an electric current flows through a conductor, a clockwise magnetic field is produced around a conductor. If a teacher decides to reverse the terminals of the battery, what would be the effect on the magnetic field?

9. Briefly explain the factors which influence the magnetic field strength of a solenoid.

2.2. Electromagnetic Induction

1. Define the term

1. Electromagnetic induction

2. Self-induction

3. Mutual induction

4. Eddy current

2. State laws of electromagnetic induction.

3. Explain how to minimize mutual induction.

4. Explain methods used to minimize eddy currents.

5. What are advantages of eddy current?

6. The transmission of power over long distance is usually done at very high voltage. Explain. A block of mass 270kg is pulled along a horizontal surface. If the coefficient of kinetic friction between the block and the surface is 0.4, what is the friction force acting on the block as it slides?

7. With aid of diagrams, explain modes of action and applications of: (i) Induction coil

   2. The a.c. generator

   3. The d.c. generator

   4. The transformer

8. Explain advantages of a.c. over d.c generators.

9. Explain why the efficiency of a transformer is usually less than 100%.

10. Discuss the factors that determine the magnitude of the induced e.m.f in a closed loop of wire.

11. In Faraday’s experiments, what would be advantage of using coil with many turns?

12. Briefly explain why a galvanometer connected to a coil deflects when a magnet is moved towards the coil.

13. Two circular coils X and Y are placed close to each other. If the current in coil X is changed, will some current be induced in the coil Y? Explain.

14. A transformer is used to step down 240 V mains supply to 12 V for laboratory use. If the primary coil has 600 turns, determine the number of turns in the secondary coil.

15. A current of 0.6 A is passed through a step-up transformer with a primary coil of 200 turns. An output current of 0.1 A is obtained from secondary coil. Determine the number of turns and the voltage across the secondary coil, if the primary coil is connected to a 240 V source.

16. A step-up transformer has 10,000 turns in the secondary coil and 100 turns in primary coil. A current of 5.0 A flows in the primary circuit when connected to a 12.0 V supply. Calculate

1. the voltage across secondary coil

2. current in secondary coil if transformer efficiency is 90%

17. A step-down transformer has 400 turns in the primary coil and 20 turns in the secondary coil. If the primary voltage is 400 V, find the voltage output at the secondary coil.

18. The ratio of the number of turns in secondary coil in a transformer to that in the primary coil is 16:1. If the current in secondary circuit is 4 A, what is the current in the primary circuit?

19. A 20 W lamp with a resistance of 7.2 Ω uses a power supply from the secondary coil of a transformer. If the primary coil is connected to a 120 V source, (a) What is the current in the lamp when it is switched on?

2. What is the secondary voltage?

3. What is the ratio of the number of turns on the primary coil to the number of turns on the secondary coil?

4. What type of transformer is it?

20. A transformer with primary coil of 1200 turns and secondary coil 600 turns is connected to 240 V mains. If the primary current is 3.0A and secondary is 5.0A. What is its efficiency?

21. A power line from a power substation to a town some distance away, has a resistance of 0.10 ohms per kilometer. Determine the rate of energy loss in the transmission of power over 50 km at a current of 60 Amperes.

22. The resistance of a length of power transmitting cables is 10 Ω and is used to transmit 11 kV at a current of 1.0A. Determine the power loss.

3. PHYSICS OF THE ATOM

3.1. The Nucleus of An Atom

1. Describe the structure of the nucleus of the atom.

2. Write short notes about the following terms:

1. Atomic number

2. Mass number (c) Isotopes (d) Isobars.

3. Mention forces holding the nucleus.

4. Basing on Thomson’s model of an atom, explain why the atom is neutral.

5. At different times scientists have proposed various descriptions or model of the atom to match the experimental evidence available. Briefly describe:

1. The plum pudding model as proposed by J.J. Thomson.

2. The planetary model as proposed model as proposed by Rutherford.

6. For each conclusion given below, state its proof from the Rutherford’s experiment.

1. Most of the mass of the atom is concentrated in a tiny region called the nucleus.

2. The nucleus is positively charged.

7. To find out more about the structure of the atom, Rutherford decided to bombard a thin gold foil with alpha particles. The whole apparatus was in vacuum. Explain role of the following components of the experimental set up.

1. Fluorescent coating on a circular screen

2. Circular shape of screen

3. Evacuated chamber

8. One isotope of chlorine has a symbol,

   1. Determine the number of neutrons in this isotope.

   2. Calculate the charge, in coulombs on the nucleus of this isotope

9. The element tin has a total of twenty five isotopes with the lightest isotope being . Assuming that all twenty five isotopes exist and difference in mass numbers is one, write down the symbol for the heaviest isotope.

10. Draw a well labeled diagram showing the atomic structure of Hydrogen.

11. Explain the following terms

1. Mass number of an atom

2. Atomic number

12. Mention the three (3) isotopes of hydrogen.

13. If the number of electrons in an atom is 8 and the number of protons is also 8, (a) what is the atomic number of the atom?

(b) what is the net positive charge of the atom?

14. Compare the properties of electrons, protons and neutrons.

15. One isotope of sodium has the symbol,

1. Calculate the number of electrons and neutrons in this isotope.

2. Calculate the charge, in coulombs, of the nucleus of this isotope.

3.2. Natural Radioactivity

16. Define the following terms

1. Radioactivity

2. Natural radioactivity

3. Nuclear decay

4. Half-life

16. Explain types of nuclear decay.

17. Describe properties of nuclear radiation.

18. State laws of radioactive decay.

19. Explain applications of natural radioactivity.

20. Explain how nuclear radiation is detected through:

1. The Spark counter

2. Photographic plate

3. The Geiger- Müller counter

4. The Wilson cloud chamber

16. A sample of a radioactive element contains 120 nuclei. How many half-lives must elapse for a sample to get to 15 nuclei?

17. The half-life of Iodine-131 is 8 days. A sample contains 16 g of Iodine-131. Determine the remaining mass of iodine in the sample after decaying for 24 days.

18. A sample contains 800 g of Iodine-131. How much Iodine-131 in the sample will remain undecayed after 40 days? (The half-life of Iodine is 8 days.)

19. The half-life of ⁶⁰Co is 5 years. How much time does it take for of its initial mass to disintegrate?

20. How long will it take 600 g of Plutinium-239 (half-life 24,000 years) to decrease to

18.75 g?

16. A certain radioactive element has a half-life of 15.5 hours. If 13.125 g of the element remain undecayed after 62 hours, what was the original sample size?

17. Plutonium-239 decays with a half-life of 24,000 years. If Plutonium-239 is stored for 72,000 years, find its remaining fraction.

18. Radioactive uranium emits a -particle to become thorium. Thorium emits a particle to become praseodymium which then emits another -particle. What are atomic number, mass number and number of final atom produced?

19. Uranium decay to polonium by -particle emission at each stage via . Following this stage decayed to -particle only.

(a) Write balanced equation of the stage decay process from and determine value of x, y, z and q (b) Identify isotopes and isobars.

16. A uranium nucleus, U-238 with atomic number 92, emits two -particles and two particles and finally forms a thorium (Th) nucleus. Write the nuclear equation for this process.

17. Uranium emits an alpha particle to become another element, as shown in the following equation -particle. Determine the value of A and Z.

18. The element Thorium (Th) has atomic number 90 and mass number 234. The element decays by emitting a beta particle to form Protactinium (Pa). Write a nuclear equation for this decay.

19. A sample of a radioactive contains 120 nuclei. Calculate the number of half-life it takes for the sample to decay so that there are only 15 nuclei left undecayed

20. The half-life of a radioactive element is 10 min. calculate how long it will take for 90% of a given mass of element to decay.

21. A snap shot photograph of a cloud chamber shows 40 tracks well defined alpha particle track. A second snap shot taken 2 min later shows only 10 tracks. What is the half-life of the alpha source?

22. A snap shot photograph of a cloud chamber shows 40 tracks well defined alpha particle track. A second snap shot taken 2 min later shows only 10 tracks. What is the half-life of the alpha source?

23. A patient suffering from cancer of thyroid glands is given a dose of radioactive iodine 131, with a half-life of 8 days, to combat diseases. He is temporarily radioactive and his nurse must be changed regularly to project them. If his radiation is initially 4 times the acceptable level, how long is it before the special nursing radiations can be dropped.

24. The count rate of a radioactive indium falls from 3200 counts per minute to 200 counts per minutes in 220 minutes. Determine the half – life of the radioactive isotope.

25. If a radioactive isotope has a half –life of 2.5 hours, how long will it take for 256 grams of the isotope to decay to 32 grams?

26. A sample of a radioactive contains 120 nuclei. Calculate the number of half-life it takes for the sample to decay so that there are only 15 nuclei left undecayed.

27. What is the half-life of a radioactive material if its activity falls to 1/8 of its value in 3360 seconds?

28. Archaeologist can determine the age of organic matter by measuring the proportion of carbon -14 present in a sample. Assuming that carbon -14 has a half –life of 5600 years ,Calculate the age of a piece of wood found to contain 1/8 as much carbon -14 as in a living material.

29. A radioactive isotope M decays by emitting two alpha and beta particles to form . What is the atomic number of M? After 224 days, 1/16 of mass of M remained. Determine the half-life of M.

30. A Geiger Muller tube connected to rate meter is hold near a radioactive source, the corrected count rate (allowing for Background count rate is 400 c.p.s. 40 min the corrected count rate is 25c.p.s. What is the half-life of the source?

31. A rate meter records a background count rate of 2 c.p.s, when a radioactive source is held near the count rate is 162 c.p.s. if the half-life of the source is 5 min. what will the recorded count rate be 20 min?

32. The activity of a radioactive element when measured using the Geiger Muller tube was found to be 63 counts per minute. Given that the background radiation was 8 counts per minute, determine

1. The actual activity of the radioactive element (Actual Activity = 63 – 8=55 c.p.m)

2. The half –life of the element if the activity dropped from 128 counts/minute to 23 counts per minute in 6 hours

16. A certain radioactive material has a half-life of 2 minutes. If the initial count rate is 256 per minutes

(i) How long does it take to reach a count rate of 32 per minutes (ii) What fraction of the original number of atoms is left undecayed?

16. A radioactive element was an initial count rate of 1200 counts per minutes measured by a scale and this falls to 150 counts per minute in 15hours (i) Determine half-life of the element.

(ii) If the initial number of an atom in another sample of this element is 3 x 1020. How many atoms will have decayed in 25 hours?

16. The half-life of thorium - 234 is 24 days. The physics department of the West Indies in Jamaica bought a sample of this thorium from England on the day of dispatch its activity was 4 x 105c.p.s

1. What was the activity of source when it arrived in Jamaica 72 days later?

2. What safety precaution should be suppliers have taken to ensure that of dude workers would be harmed

16. The following reaction is part of a radioactive series. Identify the reaction x and determine the values of c and z

3.3. Artificial Radioactivity

1. Distinguish between natural and artificial radioactivity.

2. Describe methods of producing artificial radioactive isotopes.

3. Explain applications of artificial radioactivity.

4. In each of the nucleus reaction listen below what is the atomic number, mass number and a name of the particle produced?

   1. Born bombarded with a neutron gives lithium particle.

   2. aluminium bombarded by -particle to give silicon particle.

   3. sodium bombarded by -particle to give aluminium particle. (iv) chlorine bombarded with proton gives sulphur particle.

3.4. Radiation Hazards and Safety

1. Explain the effects of nuclear radiations on human body.

2. Explain the precautions from nuclear radiation hazards.

3.5. Nuclear Reactions

1. Write short notes about the following terms:

1. Nuclear fission

2. Nuclear fusion

3. Nuclear chain reaction 2. Explain applications of nuclear reactions.

4. THERMIONIC EMISSION

4.1. Cathode Rays

1. What is thermionic emission?

2. Explain factors affecting thermionic emission.

3. Draw a well labeled diagram of a cathode ray tube.

4. With help of well labeled diagram explain how cathode rays are produced.

5. Describe the properties of cathode rays.

6. Explain applications of cathode rays.

7. Give any four uses of cathode ray oscilloscope (CRO).

8. What method in a device using the thermionic emission principle ensures that the electrons produced

   1. Do not accumulate at the source?

   2. Reach their range undeviated?

   3. Travel without meet other forms of particles on their way to the target?

9. Explain why cathode ray tube (CRT) are evacuated.

10. Draw a well labelled diagram of a cathode ray oscilloscope.

4.2. X-rays

1. Draw a well labeled diagram of a x-ray tube.

2. With help of well labeled diagram explain how x-rays are produced.

3. Describe the properties of x-rays.

4. Explain applications of cathode rays

5. Distinguish between hard and soft x-rays.

6. X – Rays are said to have harmful effect to human beings when used for a long time.

Explain the effect that X – rays cause to human beings.

7. State two ways in which x – rays differ from gamma rays.

8. In the production of X – rays what are role of:

   1. Low voltage

   2. High voltage?

   3. Tungsten target?

9. How is hard X – rays produced?

5. ELECTRONICS

5.1. Semiconductors

1. What is electronics?

2. Explain applications of electronics.

3. Explain the band theory in solid materials.

4. With help of diagram describe the features of the following by using band theory:

   1. Conductor

   2. Semiconductor

   3. Insulator

5. Describe the effects of temperature on the conductivity of :- (a) Conductors

(b) Semiconductors (c) Insulators.

6. Explain types of semiconductors.

7. What is doping?

8. With help of diagrams explain the mechanism of doping to produce n-type and p-type semiconductors.

9. What is the primary difference in the band structure of semiconductors as compared to insulators?

10. Why are there equal numbers of the electrons and holes in an intrisic semiconductor?

11. If a small number of impurities alters the electrons or hole concentrations in an intrisic semiconductor, how would this affect the electrical conductivity at low temperature?

12. How could electrical conductivity be used to determine whether a material is a conductor or semiconductor?

13. Distinguish between;

    1. Intrinsic and extrinsic semiconductors. (b) p-type and n-type semiconductors.

5.2. Diodes

1. What is p-n junction?

2. With help of diagrams explain the mode of action of p-n junction.

3. What is biasing?

4. Describe the process of biasing a p-n junction.

5. What is diode?

6. Explain five (5) types of diodes and their applications?

7. What is rectification?

8. With help of diagrams describe: (a) Half-wave rectification

(b) Full-wave rectification

9. Make a sketch of the output voltage against time for half-wave rectification. Explain why the output flows in pulses.

10. Describe and explain how a full-wave rectification is achieved by using two diodes.

5.3. Transistor

1. What is transistor?

2. Mention two (2) types of transistors.

3. With help of diagrams explain the mode of action of:

1. PNP transistor

2. NPN transistor

4. Explain the applications of transistors in daily life.

5. The diagram below shows a circuit in which important components A and B are removed

i. What does A and B represents? ii. Describe briefly the purpose of component A and B

iii. Draw a well labeled circuit diagram for the circuit above

5.4. Single Stage Amplifier

1. Write the short notes about:- (a) Analogue signals

   2. Digital signals

   3. Electrons amplifiers

   4. Single stage amplifiers

2. With help of diagrams describe the modes of action of three (3) types of single stage amplifiers.

6. ELEMENTARY ASTRONOMY

6.1. Introduction to Astronomy

1. What is astronomy?

2. Who is astronomer?

3. Explain the importance of astronomy in our daily life.

6.2. Solar system

1. Define the following terms with examples:-

   1. Universe

   2. Galaxy

   3. Stars

   4. Solar system

   5. Planet

2. Briefly explain the composition of the universe.

3. Mention and describe briefly the galaxy to which our solar system belongs and explain its shape.

4. Describe the structure of the sun.

5. Describe theories of the solar system.

6. Differentiate Rocky terrestrial from Jovian planets.

7. Mention characteristics used to name a celestrial object as a planet.

8. Differentiate planets from stars.

9. Mention other celestial bodies in solar system apart from planets.

10. What force prevents the solar system from breaking apart?

11. What is an exoplanet?

12. Why is Pluto is no longer regarded as a planet?

13. What is difference between gravity and gravitational force.

14. State Newton’s Universal law of gravitation.

15. Describe why the weight of an object on the Earth is larger than the weight of the same object placed on the Moon and Mars.

6.3. Constellations

1. What is constellation?

2. Mention five (5) common constellation.

3. Explain uses of constellations.

6.4. The Earth and it’s Moon 1. What is the moon?

2. Describe the surface features of the moon.

3. What are ocean tides? Explain the causes of them.

4. Explain types of ocean tides based on (a) height; and

   2. lunar phase.

5. Explain importance of tides.

6. With aid of diagrams describe the following terms:- (a) Apogee

   2. Perigee

   3. Lunar highlands

   4. Maria

7. Explain why tides occur twice a day

7. PHYSICS OF THE EARTH AND ITS ATMOSPHERE

7.1. Structure and Composition of the Earth

1. What is Geophysics?

2. Describe the structure of the earth.

3. With help help of diagrams describe the composition of the layers of the earth and explain the importance of each layer.

4. What is a tectonic plate?

5. Diffentiate between oceanic crust and continental crust.

6. What is the main mechanism of heat transfer from the core of the Earth to the outer regions of the Earth?

7. Explain the compositions of different layers of the interior of the Earth.

8. Explain the importance of the three (3) main layers of of the solid Earth.

9. Describe three (3) main types of tectonic plate boundaries.

10. Among the three layers of the internal structure of the Earth, which is the densest layer? Why?

7.2. Earthquakes and Volcanoes

1. What is volcano?

2. With help of diagrams explain the origin of volcano.

3. Describe the effects of volcanic eruption.

4. What is an earthquake?

5. With help of diagrams explain the origin of earthquake.

6. What is a seismic wave?

7. Distinguish between p-wave and s-wave.

8. Describe the principle of measurement of earthquake.

9. With help of diagram describe the structure and explain the mode of action of a seismograph.

10. Explain hazards of earthquake.

11. What are possible indicators for an earthquake occurance?

12. Describe precautions to be taken during an earthquake.

13. Why some volcanoes called active although they are not erupting?

14. Explain how an earthquake occurs.

15. Does the magnitude and intesity of eartquake mean the same or not? Explain.

16. Describe two types of seismic waves.

17. Explain various ways of recording the motion of the pendulum in a seismograph.

18. A seismometer located in Dodoma recorded an earthquake which originated in Mbeya. Which type of wave was recorded first? Give reasons for your choice.

7.3. Structure and Composition of the Atmosphere

1. What is an atmosphere?

2. Describe the vertical structure of the atmosphere.

3. Describe the composition of the atmosphere.

4. Explain the importance of layers of the atmosphere.

5. Brefly explain the importance of stratosphere to living things on Earth’s surface.

6. What is the importance of the large number of free electron in the ionosphere?

7. Why is it important for a captain of an aircraft to know the height of the tropopouse?

7.4. The Greenhouse Effect and Global Warming

1. Write short notes about greenhouse effect.

2. Identify greenhouse gases and their sources.

3. What is the global warming?

4. Explain the occurrence of global warming.

5. Explain consequences of global warming.

6. Explain solutions to global warming.

7. In your village, people are complaining on the increase of temperature nowdays.

   1. What are going to explain to them about the possible causes of the prevailing temperature?

   2. Clarify to them, the measures to be taken to mitigate the situation.

8. How can planting trees reduce the carbondioxide in the atmosphere?

9. You are working at a village where people are mainly using charcoal as a source of energy. explain to them the effects that arise to the environment as a result of prolonged use of charcoal.

10. Explain side effects of industrial development with respect to global warming.

11. Explain why radiation originating from the Earth is termed as long wave radiation.

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