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Secondary 3 Physics Waves Sound Light Quiz
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Questions
Secondary 3 Physics Quiz - Waves Sound Light
Name: ________________________
Class: ________________________
Date: ________________________
Score: ______ / 40
Duration: 50 minutes
Total Marks: 40
Instructions:
- Answer ALL questions.
- Write your answers in the spaces provided.
- Show all working clearly for calculation questions.
- The number of marks for each question or part-question is shown in brackets [ ].
- You may use a calculator where appropriate.
- This quiz is based on the Waves, Sound and Light topic from the Secondary 3 Physics syllabus.
Section A: Multiple Choice (Questions 1–5) [10 marks]
For each question, choose the most correct answer (A, B, C, or D).
1. Which of the following is a transverse wave?
A. Sound wave in air
B. Wave on a stretched string
C. Ultrasound wave in water
D. Compression wave in a spring
[1 mark]
2. A wave has a frequency of 200 Hz and a wavelength of 1.5 m. What is the speed of the wave?
A. 133 m/s
B. 200 m/s
C. 300 m/s
D. 450 m/s
[1 mark]
3. Which property of a sound wave determines its loudness?
A. Frequency
B. Wavelength
C. Amplitude
D. Speed
[1 mark]
4. Light travels from air into glass. Which of the following statements is correct?
A. The speed of light increases, and the wavelength increases.
B. The speed of light decreases, and the wavelength decreases.
C. The speed of light decreases, and the frequency increases.
D. The speed of light increases, and the frequency decreases.
[1 mark]
5. A student stands 85 m from a wall and claps her hands. She hears the echo 0.50 s later. What is the speed of sound in air based on this measurement?
A. 170 m/s
B. 340 m/s
C. 425 m/s
D. 680 m/s
[1 mark]
Section B: Short Answer and Structured Questions (Questions 6–15) [20 marks]
6. State two differences between transverse waves and transverse waves.
(a) _______________________________________________________________ [1 mark]
(b) _______________________________________________________________ [1 mark]
7. The diagram below shows a wave pattern at one instant in time.
↑ displacement
| /\ /\
| / \ / \
| / \ / \
| / \/ \
------+------------------------→ distance
| /\
| / \
| / \
(a) On the diagram, label the amplitude of the wave. [1 mark]
(b) On the diagram, label one wavelength. [1 mark]
8. Define the frequency of a wave. _______________________________________________________________ [1 mark]
9. A wave has a speed of 12 m/s and a frequency of 4.0 Hz. Calculate the wavelength of the wave.
Working: _______________________________________________________________
Answer: _________________ [2 marks]
10. Explain why sound cannot travel through a vacuum. _______________________________________________________________ [2 marks]
11. A student uses a ripple tank to study water waves. She observes that the waves pass through a gap and spread out.
(a) Name this phenomenon. _______________________________________________________________ [1 mark]
(b) State one factor that affects the amount of spreading. _______________________________________________________________ [1 mark]
12. The speed of sound in air is 340 m/s. A lightning strike occurs 1.7 km away from an observer.
(a) Calculate how long it takes for the sound of thunder to reach the observer.
Working: _______________________________________________________________
Answer: _________________ [2 marks]
(b) Explain why the observer sees the lightning before hearing the thunder. _______________________________________________________________ [1 mark]
13. State two properties that distinguish light waves from sound waves.
(a) _______________________________________________________________ [1 mark]
(b) _______________________________________________________________ [1 mark]
14. A sound wave has a frequency of 440 Hz and travels at 330 m/s in air. Calculate the wavelength of this sound wave.
Working: _______________________________________________________________
Answer: _________________ [2 marks]
15. Describe what happens to the pitch and loudness of a sound wave when:
(a) The frequency increases: _______________________________________________________________ [1 mark]
(b) The amplitude decreases: _______________________________________________________________ [1 mark]
Section C: Application and Explanation Questions (Questions 16–20) [10 marks]
16. The diagram shows a ray of light travelling from air into a glass block.
Air
─────────────────
| /
→ | / ← reflected ray
ray |/
─────────────────
|\
| \ → refracted ray
| \
Glass
(a) Name the phenomenon that causes the light to change direction as it enters the glass. _______________________________________________________________ [1 mark]
(b) Name the phenomenon that causes part of the light to bounce back into the air. _______________________________________________________________ [1 mark]
(c) State whether the speed of light increases or decreases as it enters the glass. _______________________________________________________________ [1 mark]
17. A student sets up an experiment to measure the speed of sound using echoes. She stands at a distance d from a large wall and claps once. She measures the time t between the clap and the echo.
(a) Write an equation for the speed of sound v in terms of d and t. _______________________________________________________________ [1 mark]
(b) Explain why the student should measure the time for several echoes and take an average. _______________________________________________________________ [1 mark]
18. The electromagnetic spectrum includes the following types of waves (in order of increasing frequency): radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
(a) Which type of electromagnetic wave has the longest wavelength? _______________________________________________________________ [1 mark]
(b) State one use of infrared radiation. _______________________________________________________________ [1 mark]
19. A guitar string is plucked and produces a sound wave. Explain, in terms of wave properties, how the following changes affect the sound produced:
(a) The string is tightened (increasing the tension). _______________________________________________________________ [1 mark]
(b) A thicker string is used instead. _______________________________________________________________ [1 mark]
20. A student observes that when a police car with its siren on drives past her, the pitch of the siren appears to change.
(a) Name this phenomenon. _______________________________________________________________ [1 mark]
(b) Describe how the pitch changes as the car approaches and then moves away. _______________________________________________________________ [1 mark]
END OF QUIZ
Answers
Secondary 3 Physics Quiz - Waves Sound Light
Answer Key
Section A: Multiple Choice
1. B — Wave on a stretched string [1 mark]
Explanation: In a transverse wave, the direction of vibration is perpendicular to the direction of wave travel. A wave on a stretched string vibrates up and down while the wave travels horizontally. Sound waves in air and ultrasound in water are longitudinal waves. A compression wave in a spring is also longitudinal.
2. C — 300 m/s [1 mark]
Working: v = f × λ = 200 × 1.5 = 300 m/s
Common mistake: Students may divide instead of multiply (200 ÷ 1.5 = 133 m/s — option A is a trap).
3. C — Amplitude [1 mark]
Explanation: The amplitude of a sound wave determines its loudness. A larger amplitude means a louder sound. Frequency determines pitch, not loudness.
4. B — The speed of light decreases, and the wavelength decreases. [1 mark]
Explanation: When light enters a denser medium (glass), it slows down. The frequency remains constant, so since v = fλ, a decrease in speed means the wavelength must also decrease. Frequency does not change when light moves from one medium to another.
5. B — 340 m/s [1 mark]
Working: The sound travels to the wall AND back, so total distance = 2 × 85 = 170 m.
v = d ÷ t = 170 ÷ 0.50 = 340 m/s
Common mistake: Forgetting to double the distance (using 85 m instead of 170 m gives 170 m/s — option A is a trap).
Section B: Short Answer and Structured Questions
6. Two differences between transverse waves and longitudinal waves: [2 marks]
(a) In transverse waves, the vibration is perpendicular to the direction of wave travel; in longitudinal waves, the vibration is parallel to the direction of wave travel. [1 mark]
(b) Transverse waves have crests and troughs; longitudinal waves have compressions and rarefactions. [1 mark]
Marking note: Accept any two valid differences. Other acceptable answers include: transverse waves can be polarised but longitudinal waves cannot; transverse waves travel through solids and on surfaces of liquids, while longitudinal waves travel through solids, liquids, and gases.
7. [2 marks]
(a) Amplitude labelled correctly — the maximum displacement from the equilibrium (central) line to the peak (or trough) of the wave. [1 mark]
(b) Wavelength labelled correctly — the distance between two consecutive identical points on the wave (e.g., crest to crest, or trough to trough). [1 mark]
Marking note: Accept any clear and correct labelling on the diagram.
8. Frequency is the number of complete waves (or oscillations) produced per second (or passing a point per second). [1 mark]
Accept: "Number of waves per second" or equivalent.
Marking note: The answer must convey the idea of "per second" or "in one second" to receive the mark.
9. [2 marks]
Working:
v = f × λ
λ = v ÷ f = 12 ÷ 4.0 = 3.0 m
Answer: 3.0 m [2 marks — 1 mark for correct substitution, 1 mark for correct answer with unit]
Marking note: Award 1 mark if the formula is correctly rearranged and values substituted but the final answer has a calculation error. Award full marks only for correct answer with unit.
10. Sound is a mechanical (longitudinal) wave that requires a medium (solid, liquid, or gas) to travel. [1 mark] In a vacuum, there are no particles to vibrate and pass the energy along, so sound cannot propagate. [1 mark]
Marking note: Both marks require clear reasoning. Simply saying "there is no medium" without explanation earns only 1 mark.
11. [2 marks]
(a) Diffraction [1 mark]
(b) The width of the gap (relative to the wavelength). [1 mark]
Accept: "Wavelength of the wave" — the amount of diffraction increases when the gap width is similar to the wavelength.
12. [3 marks]
(a) Working:
Distance = 1.7 km = 1700 m
v = d ÷ t, so t = d ÷ v = 1700 ÷ 340 = 5.0 s
Answer: 5.0 s [2 marks — 1 mark for correct substitution/conversion, 1 mark for correct answer with unit]
Marking note: Award 1 mark if the student converts 1.7 km to 1700 m correctly and substitutes into the formula, even if the final division is incorrect.
(b) Light travels much faster than sound (speed of light ≈ 3 × 10⁸ m/s, speed of sound ≈ 340 m/s), so the light from the lightning reaches the observer almost instantly while the sound takes a noticeable time. [1 mark]
13. Two properties distinguishing light waves from sound waves: [2 marks]
(a) Light waves are transverse; sound waves are longitudinal. [1 mark]
(b) Light can travel through a vacuum; sound cannot. [1 mark]
Accept: "Light travels much faster than sound" or "Light is an electromagnetic wave; sound is a mechanical wave."
14. [2 marks]
Working:
v = f × λ
λ = v ÷ f = 330 ÷ 440 = 0.75 m
Answer: 0.75 m [2 marks — 1 mark for correct substitution, 1 mark for correct answer with unit]
15. [2 marks]
(a) When the frequency increases, the pitch of the sound increases (becomes higher). [1 mark]
(b) When the amplitude decreases, the loudness of the sound decreases (becomes quieter). [1 mark]
Section C: Application and Explanation Questions
16. [3 marks]
(a) Refraction [1 mark]
(b) Reflection [1 mark]
(c) The speed of light decreases. [1 mark]
Explanation: Glass is optically denser than air, so light slows down when entering glass.
17. [2 marks]
(a) v = 2d ÷ t [1 mark]
Explanation: The sound travels to the wall and back, so the total distance is 2d.
(b) Taking multiple measurements and averaging reduces the effect of random errors (e.g., reaction time in starting/stopping the timer), making the result more accurate and reliable. [1 mark]
18. [2 marks]
(a) Radio waves [1 mark]
(b) Any one use of infrared radiation, e.g.: remote controls, thermal imaging cameras, night-vision equipment, infrared heaters, optical fibre communication. [1 mark]
19. [2 marks]
(a) When the string is tightened, the tension increases, which increases the frequency of vibration. This produces a sound with a higher pitch. [1 mark]
(b) A thicker string has greater mass per unit length, which decreases the frequency of vibration. This produces a sound with a lower pitch. [1 mark]
Marking note: The explanation must link the change to frequency/pitch. Simply stating "the pitch changes" without explanation earns no mark.
20. [2 marks]
(a) The Doppler effect [1 mark]
(b) As the car approaches, the pitch appears higher than the actual frequency. As the car moves away, the pitch appears lower than the actual frequency. [1 mark]
Marking note: The student must describe the change in both directions (higher when approaching, lower when receding) for the mark.
Total: 40 marks