IGCSE Physics: General Properties of Waves Practice Questions
A wave transfers energy from one place to another without transferring matter. Its speed, frequency and wavelength are linked by v = f x lambda, and its behaviour at a boundary or a gap is described by reflection, refraction and diffraction.
Sub-topic 3.1 of Cambridge IGCSE Physics 0625 sets up everything that follows on light, sound and the electromagnetic spectrum. Two things earn most of the marks here: confident use of the wave equation with correct unit conversion, and precise language when describing what changes at a boundary. The questions below cover both.
What you need to know for General Properties of Waves
- Transverse waveThe oscillations are at right angles to the direction of energy transfer. Light, all electromagnetic waves and water waves are transverse.
- Longitudinal waveThe oscillations are parallel to the direction of energy transfer, producing compressions and rarefactions. Sound is longitudinal.
- Amplitude and wavelengthAmplitude is the maximum distance a point moves from its undisturbed position. Wavelength is the distance between two consecutive corresponding points on the wave, for example crest to crest.
- Frequency and periodFrequency is the number of complete waves passing a point each second, measured in hertz. Period is the time for one complete wave, and f = 1 / T.
- The wave equationWave speed = frequency x wavelength, written v = f x lambda, with v in m/s, f in Hz and wavelength in m.
- RefractionA wave changes speed when it crosses a boundary between two media. If it meets the boundary at an angle, the change in speed causes a change in direction. Frequency stays the same, so wavelength changes with speed.
IGCSE Physics General Properties of Waves questions and answers
4 exam-style questions written to the 0625 syllabus. Try each one on paper first, then open the worked answer to check your method against the marks.
A water wave has a frequency of 5.0 Hz and a wavelength of 0.40 m. Calculate the speed of the wave and its period.
Show the worked answer
- Use the wave equation v = f x lambda.
- v = 5.0 x 0.40 = 2.0 m/s.
- Use T = 1 / f for the period.
- T = 1 / 5.0 = 0.20 s.
State two differences between transverse and longitudinal waves and give one example of each.
Show the worked answer
- In a transverse wave the particles oscillate at right angles to the direction of energy transfer. In a longitudinal wave they oscillate parallel to it.
- A transverse wave has crests and troughs. A longitudinal wave has compressions and rarefactions.
- Example of a transverse wave: light, or any electromagnetic wave, or a water wave.
- Example of a longitudinal wave: sound.
Water waves travel from deep water into shallow water and change direction at the boundary. Explain why, and state what happens to the frequency and the wavelength.
Show the worked answer
- Water waves travel more slowly in shallow water than in deep water.
- Because the wave meets the boundary at an angle, one side of each wavefront slows before the other, so the wave changes direction. This is refraction.
- The frequency is set by the source and does not change when the wave crosses a boundary.
- Since v = f x lambda and the speed falls while frequency stays constant, the wavelength must decrease.
Describe what happens to a water wave as it passes through a gap in a barrier when the gap is about the same width as the wavelength.
Show the worked answer
- When a wave passes through a gap it spreads out. This is diffraction.
- The amount of spreading depends on the size of the gap compared with the wavelength.
- When the gap is roughly equal to the wavelength, the spreading is greatest and the waves fan out in circular arcs beyond the gap.
- The wavelength, frequency and speed are all unchanged by diffraction.
Common mistakes in this topic
- Measuring wavelength from a crest to a trough. That is half a wavelength.
- Confusing amplitude with wave height. Amplitude is measured from the undisturbed position to a crest, not from trough to crest.
- Saying frequency changes during refraction.
- Forgetting to convert centimetres or kilohertz before using the wave equation.
- Describing sound as a transverse wave, or claiming sound travels through a vacuum.
Exam tips
- Write v = f x lambda before every wave calculation, then rearrange. Recall of the equation is often worth a mark on its own.
- Check your units first. Hz multiplied by m gives m/s, which confirms the arrangement is right.
- In refraction questions, always state what happens to speed, wavelength and frequency separately. Frequency is the constant one.
- Label diagrams with wavefronts rather than rays when a question uses a ripple tank.
- For diffraction, compare the gap size to the wavelength explicitly. That comparison is where the mark sits.
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General Properties of Waves FAQs
What is the wave equation for IGCSE Physics?
Wave speed equals frequency multiplied by wavelength, written v = f x lambda. Speed is in metres per second, frequency in hertz and wavelength in metres. Rearranged forms are f = v divided by lambda, and lambda = v divided by f.
Does frequency change when a wave enters a new material?
No. Frequency is determined by the source and stays the same when a wave crosses a boundary. The speed changes, and because speed equals frequency multiplied by wavelength, the wavelength must change in proportion. This is the key idea behind refraction questions.
What is the difference between diffraction and refraction?
Refraction is the change in direction caused by a change in wave speed when the wave crosses a boundary between two media. Diffraction is the spreading out of a wave as it passes through a gap or around an obstacle, with no change in speed or wavelength.
Why is sound a longitudinal wave?
Sound travels as a series of compressions and rarefactions in which particles of the medium oscillate backwards and forwards along the same direction the energy travels. Because the oscillation is parallel to the direction of energy transfer, sound is longitudinal, and because it needs particles it cannot travel through a vacuum.
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Written to the published Cambridge IGCSE Physics (0625) syllabus. Check your school entry code and syllabus year, because Core and Extended candidates are assessed on different content. Last reviewed 2026-08-12.