Waves

In order to understand Waves, lets think about water waves

Waves are temporary displacement in something, in this case water. The water starts off level. This is the Equilibrium Point. Everything is balanced.

As the energy the waves carry increases, the amount of displacement increases.

The maximum amount of displacement is called The Amplitude

The amplitude is measured from the equilibrium point Amplitude This means it is equal both above and below

The distance between peaks is called The Wavelength

Wavelength This can be measured between any like parts of a wave

Waves are of course travelling Although the matter itself doesn’t move far

We can measure how many waves pass in a bit of time This is the wave’s frequency and normally measured in hertz - how many per second -

We can also measure how long it takes for one wave to pass a point This is the waves period and normally measured in seconds

If we know how long one wavelength is and we know how many waves there are per second We can calculate the length per second – or speed of the wave

This is done using the wave equation: c = λ f where c=Wave speed in metres per second, m/s λ=Wavelength in metres, m f=Frequency in Hertz, Hz

For example: If a wave has a wavelength of 10 m and frequency of 4 Hz, what is its wave speed? 1. Cover what you want to find c = f x λ 2. Write down what’s left 3. Substitute in numbers c = 4 x Calculate answer c = 40 m/s 5. Add units

For example: If a wave has a wave speed of 5 m/s and frequency of 10 Hz, what is its wavelength? 1. Cover what you want to find λ = c / f 2. Write down what’s left 3. Substitute in numbers λ = 5 / Calculate answer λ = 0.5 m 5. Add units

For example: If a wave has a wave speed of 10 m/s and wavelength of 4 m, what is its frequency? 1. Cover what you want to find f = c / λ 2. Write down what’s left 3. Substitute in numbers f = 10 / 4 4. Calculate answer f = 2.5 Hz 5. Add units

There are two types of wave Transverse Displacement is at right angles with the direction that the wave is travelling Direction of wave

and Longitudinal Displacement is in line with the direction that the wave is travelling Direction of wave