Form 4 Physics imtixaanka qaranka 2018 iyo jawaabihiisa

PART ONE: Multiple Choice (40 marks)

Answer all questions. Circle the correct answer.

1. 1

   Which of the following electromagnetic waves has the highest frequency?

   • A.X-ray
   • B.Gamma ray
   • C.Ultraviolet
   • D.Infrared waves

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2. 2

   Beta particles are actually

   • A.Protons
   • B.Electrons
   • C.Neutrons
   • D.Neutral

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3. 3

   Which of the following is an application of radioactivity?

   • A.Fission
   • B.Fussion
   • C.Half-life
   • D.Carbon dating

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4. 4

   The image formed by a convex mirror is always

   • A.Real
   • B.Virtual
   • C.Same size
   • D.Magnified

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5. 5

   The region of total darkness formed behind an opaque body is called:

   • A.penumbra
   • B.Convergent beam
   • C.Umbra
   • D.Divergent beam

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6. 6

   A substance that does not allow light energy to pass through it is called

   • A.Transparent
   • B.Opaque
   • C.Luminous
   • D.Translucent

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7. 7

   Rainbow is formed due to:

   • A.Interference of light
   • B.Absorption of light
   • C.Dispersion of light
   • D.Diffraction of light

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8. 8

   A ray of light R strikes normal to a plane mirror as shown in the figure. Which of the rays A, B, C or D represents the correct reflected ray?

   

   • A.A
   • B.B
   • C.C
   • D.D

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9. 9

   An object O is placed in front of a plane mirror as shown. Which of the points A, B, C or D will the observer see the image of the object in the plane mirror

   

   • A.A
   • B.B
   • C.C
   • D.D

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10. 10

    A student shakes the end of a rope with a frequency of 1.5 Hz, causing waves with a wavelength of 0.8 m to travel along the rope. What is the velocity of the waves?

    • A.1.9 m/s
    • B.1.6 m/s
    • C.1.2 m/s
    • D.5.3 m/s

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11. 11

    The following diagram shows a wave. [The 12 m marked on the diagram runs from the first crest to the third crest; 0.2 m is marked from crest to trough.] Which row in the table gives the wavelength and amplitude of the wave?

    

    • A.Wavelength 4 m, Amplitude 0.2 m
    • B.Wavelength 6 m, Amplitude 0.1 m
    • C.Wavelength 6 m, Amplitude 0.2 m
    • D.Wavelength 12 m, Amplitude 0.1 m

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12. 12

    The diagram below represents a wave. [Displacement between 0.20 m and -0.20 m; three complete waves span 6.0 m.] What is the speed of the wave if its frequency is 8.0 hertz?

    

    • A.48 m/s
    • B.3.2 m/s
    • C.16 m/s
    • D.1.6 m/s

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13. 13

    The diagram shows how displacement varies with time as a wave passes a fixed point. What is the frequency of this wave?

    

    • A.0.25Hz
    • B.0.50Hz
    • C.1.0Hz
    • D.2.0Hz

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14. 14

    The loudness of a sound is determined mainly by its

    • A.amplitude.
    • B.speed.
    • C.frequency.
    • D.pitch.

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15. 15

    What is the wavelength of a 264-Hz sound wave when the speed of sound is 345 ?

    • A.0.77 m
    • B.1.31 m
    • C.6.09 m
    • D.9.11 m

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16. 16

    Waves that are produced on a guitar string by plucking it are

    • A.sound waves
    • B.acoustic waves
    • C.transverse waves
    • D.longitudinal waves

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17. 17

    What is the kinetic energy of an object with a mass of 10 kilograms traveling at a speed of 10 meters per second?

    • A.100 J
    • B.500 J
    • C.1000 J
    • D.5,000 J

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18. 18

    Which of the following radiations is used for sterilizing food

    • A.Alpha ray
    • B.X-ray
    • C.Gama ray
    • D.Beta ray

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19. 19

    Which of the following is NOT radioactive detector

    • A.Geiger Muller Tube
    • B.Cloud Chamber
    • C.Joule meter
    • D.Spark counter

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20. 20

    The half-life of a radioactive material is 24 years. The activity of a sample falls to a fraction of its initial value after 72 years. What is the fraction?

    • A.1/3
    • B.1/4
    • C.1/6
    • D.1/8

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PART 2: (60 marks) Answer all questions

1. B1a

   Question 1 - Oscillatory Motion. Fill in the blank spaces with a suitable word. a) The ratio of the external force acting on a spring to the extension is called _____

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2. B1b

   Question 1 - Oscillatory Motion. Fill in the blank spaces with a suitable word. b) The motion of a body about their mean position is known as _____

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3. B1c

   Question 1 - Oscillatory Motion. c) The length of a spring is 8cm. When a mass of 4kg is hung to it, its length becomes 16cm. The spring constant is?

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4. B2i

   Question 2: Waves. Mohamed shakes a rope up and down to produce a wave as shown below. The waves are not reflected by the wall. (i) Draw an arrow on the diagram to show the direction in which the waves transfer energy.

   

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5. B2ii

   Question 2: Waves. Mohamed shakes a rope up and down to produce a wave as shown below. The waves are not reflected by the wall. (ii) The waves produced on the rope are transverse. Name one other type of transverse wave.

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6. B2iii

   Question 2: Waves. Mohamed shakes a rope up and down to produce a wave as shown below. The waves are not reflected by the wall. (iii) The rope is shaken up and down, producing 3 waves every second. The waves have a wavelength of 1.5 metres. State the frequency of the waves.

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7. B2iv

   Question 2: Waves. Mohamed shakes a rope up and down to produce a wave as shown below. The waves are not reflected by the wall. (iv) Calculate the speed of the waves. (The rope produces 3 waves every second with a wavelength of 1.5 metres.)

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8. B3.1

   Question 3: Sound. 1. Name any two sources of sound waves

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9. B3.2a

   Question 3: Sound. 2. a) A musical instrument produces a sound wave with a frequency of 1000 Hz. The sound wave has a wavelength of 0.34 m in air. Calculate the speed of the sound wave in air. (v = λf)

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10. B3.2b

    Question 3: Sound. b) In water the speed of sound is different. The speed of a sound wave in water is 1300 m/s. The sound wave has a frequency of 1000Hz. Calculate the wavelength of this sound wave.

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11. B3.2c

    Question 3: Sound. c) The diagram shows a ship using an Echo locator (SONAR) to find a shoal of fish near Mogadishu in the Indian Ocean. The pulsed wave is transmitted from the ship, which is then reflected off the top of the shoal and is then picked up by the receiver. The time taken to receive the echo is 3s after transmission and the speed of sound in water is 1500m/s. Calculate how deep the ship has to lower its fishing nets to catch the top of the shoal.

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12. B3.2d

    Question 3: Sound. (d) Define the term 'ultrasound wave'

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13. B3.2e

    Question 3: Sound. (e) Give one other use of ultrasound waves (apart from echo location)

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14. B4.1

    Question 4: Properties of light. 1. Define the term light.

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15. B4.2

    Question 4: Properties of light. 2. What are the three important characteristics of light?

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16. B4.3a

    Question 4: Properties of light. 3. The diagram below shows a partly drawn ray-tracing diagram (an object placed in front of a converging lens, beyond twice the focal length, with one ray parallel to the axis and one ray through the focus). (a) Complete the ray-tracing diagram.

    

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17. B4.3bi

    Question 4: Properties of light. 3. The diagram below shows a partly drawn ray-tracing diagram (an object placed in front of a converging lens, beyond twice the focal length, with one ray parallel to the axis and one ray through the focus). (b) Is the image produced (i) real or virtual?

    

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18. B4.3bii

    Question 4: Properties of light. 3. The diagram below shows a partly drawn ray-tracing diagram (an object placed in front of a converging lens, beyond twice the focal length, with one ray parallel to the axis and one ray through the focus). (b) Is the image produced (ii) upright or inverted?

    

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19. B4.3biii

    Question 4: Properties of light. 3. The diagram below shows a partly drawn ray-tracing diagram (an object placed in front of a converging lens, beyond twice the focal length, with one ray parallel to the axis and one ray through the focus). (b) Is the image produced (iii) enlarged or diminished?

    

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20. B5.1

    Question 5: Dispersion of Light. 1. White light is a mixture of seven colours. Name them.

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21. B5.2

    Question 5: Dispersion of Light. 2. Define the term dispersion of light.

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22. B5.3a

    Question 5: Dispersion of Light. 3. a) What is a spectrum?

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23. B5.3b

    Question 5: Dispersion of Light. b) Below is a diagram of a prism. For each line, indicate the colour that appears on the white screen from number 1 to 7 in the diagram.

    

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24. B5.3c

    Question 5: Dispersion of Light. c) What is meant by the refraction of light?

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25. B5.3d

    Question 5: Dispersion of Light. d). Which colour of the spectrum has i) Maximum refraction ii) Minimum refraction

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26. B6.1

    Question 6: Reflection of Light. 1. State the laws of reflection.

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27. B6.2

    Question 6: Reflection of Light. 2. If a person stands 4m from a plane mirror, what is the distance between the person and his image?

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28. B6.3

    Question 6: Reflection of Light. 3. State two uses of convex mirrors.

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29. B7.1

    Question 7: Refraction of Light. 1. State Snell's law of refraction.

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30. B7.2

    Question 7: Refraction of Light. 2. The diagram below shows a light ray travelling through air to the interface between the air and a glass block. On the diagram draw the normal, and a possible path for the ray in the glass.

    

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31. B7.3

    Question 7: Refraction of Light. 3. Explain why the sky appears blue during the day.

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Imtixaanada kale ee hore ee Form 4 Physics

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