Curriculum fit: GCSE Physics and Combined Science (waves). US: middle and high school physical science (waves and their applications).
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What is it?
A wave transfers energy without transferring matter. Waves are described by their amplitude (maximum displacement), wavelength (distance between matching points) and frequency (waves per second, in hertz).
Transverse waves, such as light, have vibrations at right angles to the direction of travel. Longitudinal waves, such as sound, have vibrations along the direction of travel.
Key formulas and ideas
- Wave speed v = frequency f × wavelength λ.
- Frequency f = 1 ÷ period T.
- Electromagnetic spectrum, low to high frequency: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma.
- All electromagnetic waves travel at about 3 × 10^8 m/s in a vacuum.
Worked examples
Wave equation
A wave has frequency 50 Hz and wavelength 2 m. Find its speed.
- v = f × λ.
- = 50 × 2 = 100.
✓ Answer 100 m/s
Period and frequency
A wave has a period of 0.02 s. Find its frequency.
- f = 1 ÷ T.
- 1 ÷ 0.02 = 50.
✓ Answer 50 Hz
Missing wavelength
Sound travels at 340 m/s with frequency 170 Hz. Find the wavelength.
- λ = v ÷ f.
- 340 ÷ 170 = 2.
✓ Answer 2 m
Common mistakes to avoid
- Confusing amplitude with wavelength.
- Saying that sound is a transverse wave.
- Forgetting that waves transfer energy, not matter.
- Mixing up frequency and period.
Practice questions
Frequently asked questions
Can sound travel through a vacuum?
No. Sound needs a medium such as air, water or a solid. Light and other electromagnetic waves can travel through a vacuum.
What is the difference between frequency and wavelength?
Frequency is how many waves pass a point each second, measured in hertz. Wavelength is the distance from one point on a wave to the same point on the next wave. At a fixed wave speed, a higher frequency means a shorter wavelength.
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Reviewed by StudyMorrow editorial review on 5 Nov 2026.