3.1.1

# Progressive Waves

Test yourself

## Waves - Examples

Waves transfer energy from one place to another without transferring matter. Wave motion (the movement of waves) can be shown by the vibrations of a spring or by water waves.

### Springs - transverse waves

• Hold one end of a horizontal spring in a fixed position and move the other end of the spring up and down.
• We can observe a wave moving from the end we are holding towards the fixed end of the spring.

### Water

• When a wave travels along the surface of water, a cork floating on the surface of the water will only move up and down as the wave passes.

## Frequency and Period

All waves have a frequency and a period of oscillation.

### Frequency

• Frequency is the number of oscillations (vibrations) per second.
• Frequency = number of oscillations ÷ time
• The frequency is equal to 1 divided by the period.
• Frequency = 1 ÷ period
• Frequency is measured in Hertz (Hz).

### Period

• The period of a wave is the time taken to complete one oscillation (vibration).
• It is equal to 1 divided by the frequency.
• Period = 1 ÷ frequency
• The period of a wave is measured in seconds.