Topic 3 — Waves

What is a wave?

A way of transferring energy without transferring matter overall.

What is a transverse wave?

A wave where vibrations are perpendicular to the direction of travel.

What is a longitudinal wave?

A wave where vibrations are parallel to the direction of travel.

What is wavelength?

The distance between corresponding points on consecutive waves.

What is frequency?

The number of complete waves passing a point each second.

What is the unit of frequency?

Hertz (Hz).

What is amplitude?

The maximum displacement from the equilibrium position.

What is the wave speed equation?

wave speed = frequency × wavelength

What is the period of a wave?

The time taken for one complete wave.

What is the equation linking frequency and period?

frequency = 1 ÷ period

What are the seven types of electromagnetic radiation?

Radio, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.

What is the order of the electromagnetic spectrum from lowest to highest frequency?

Radio → microwave → infrared → visible → ultraviolet → X-ray → gamma.

What do all electromagnetic waves have in common?

They are transverse waves and travel at the same speed in a vacuum.

What is the speed of electromagnetic waves in a vacuum?

3.0 × 10⁸ m/s.

What is reflection?

The bouncing back of a wave from a surface.

What is the law of reflection?

The angle of incidence equals the angle of reflection.

What is refraction?

The change in direction of a wave caused by a change in speed when it enters a different medium.

What happens when light enters a more optically dense medium?

It slows down and bends towards the normal.

What is diffraction?

The spreading of waves through a gap or around an obstacle.

When is diffraction greatest?

When the gap size is similar to the wavelength.