Transverse and Longitudinal — Physics (Grade 10)

Define and explain Transverse and Longitudinal in your own words
Use key terms such as wavelength accurately
Apply what you have learned to new examples and questions
Avoid the common mistakes learners make with this topic

Waves carry energy across the universe — from ripples on a pond to the light of distant stars. Learn their shared language of wavelength and frequency, and you can describe sound, light and everything in between.

This lesson focuses on Transverse and Longitudinal: comparing the two wave types and the direction of their vibrations.

Definition: Transverse and Longitudinal

Comparing the two wave types and the direction of their vibrations.

Key ideas

Waves carry energy without carrying matter

In a transverse wave (like light or a rope wave) the vibrations are at right angles to the direction of travel; in a longitudinal wave (like sound) they are parallel, forming compressions and rarefactions. The medium oscillates but does not travel with the wave — only energy moves onwards, which is why a floating duck bobs up and down as ripples pass.

Wave speed links frequency and wavelength

v = f × λ: speed equals frequency times wavelength. Higher frequency means more waves per second, so for a fixed speed the wavelength must shrink. Rearranging gives f = v ÷ λ and λ = v ÷ f — learn all three forms.

Key term — wavelength: The distance between two matching points on neighbouring waves, e.g. crest to crest, in metres.

Worked example: Transverse and Longitudinal

Is a sound wave transverse or longitudinal? Explain.

Longitudinal — air particles vibrate parallel to the direction the sound travels, in compressions and rarefactions.

Answer: Longitudinal — air particles vibrate parallel to the direction the sound travels, in compressions and rarefactions.

Common mistakes

Saying the medium moves along with the wave Particles oscillate in place; only energy is transferred along the wave.
Mixing up amplitude and wavelength on a diagram Amplitude is the vertical height from the middle line; wavelength is the horizontal repeat distance.

Practice

A wave has frequency 50 Hz and wavelength 4 m. Calculate its speed.

v = fλ.

50 × 4 = 200 m/s.

Red light has a longer wavelength than blue light. Which has the higher frequency?

v = fλ with v fixed.

Blue light — with speed constant, shorter wavelength means higher frequency.

Name two uses of microwaves and one danger of excessive infrared exposure.

Think kitchens, communications and heat.

Microwaves: cooking food, mobile phone and satellite communication. Infrared: overexposure can cause skin burns.

An EM wave has wavelength 0.5 m. Calculate its frequency (c = 3 × 10⁸ m/s).

f = v ÷ λ.

3 × 10⁸ ÷ 0.5 = 6 × 10⁸ Hz.

Quick check

Transverse and Longitudinal — quick check

Which of these best defines "wavelength"?

The distance between two matching points on neighbouring waves, e.g. crest to crest, in metres.

A ray of light bends as it enters glass from air. Name the effect and explain why it happens.

Refraction — light slows down in glass, and the change in speed at the boundary bends the ray.

Key takeaways

Transverse and Longitudinal: comparing the two wave types and the direction of their vibrations.
Waves carry energy without carrying matter: In a transverse wave (like light or a rope wave) the vibrations are at right angles to the direction of travel; in a longitudinal wave (like sound) they are parallel, forming compressions and rarefactions.
frequency: The number of waves passing a point per second, in hertz.
Watch out for: saying the medium moves along with the wave

The Wave Speed Equation →Back to Grade 10 chapters Related resources →