All waves can transfer energy from one place to another without transferring any matter. This is done by a series of disturbances or vibrations that carry the energy. Just like the people in their seats, only moving up and down when it’s their turn.
Waves can transfer energy through solids, liquids, gases and empty spaces – otherwise known as vacuums.
There are two types of waves – which we will look at in more detail in another video, but the basic features are the same.
The frequency of a wave is the number of complete waves passing a fixed point in a given amount of time. This time period is usually one second. Frequency is given the symbol f and is measured in units called Hertz. Hertz measure how many complete cycles per second; so how many people in our Mexican wave stand up every second.
The frequency and period are often confused. The frequency refers to how often something happens, whereas the period refers to the time it takes to happen.
The period of a wave is the time for one complete cycle. So the time taken for one person to stand up, wave and sit down. This would be measured in seconds. When something happens repeatedly we say that the event is periodic and refer to the time for the event to repeat itself. The period of the earth to orbit the sun is 365 days, the period of a day is 24 hours, the period of a typical class at school is 45 minutes.
Now for the wavelength… the wavelength is the distance between a point on one wave and the same point on the next wave, for example two peaks or two troughs. Wavelength is given the symbol Lambda from the Greek letter, and is usually measured in metres.
Wavelengths can vary hugely in size, x-rays are very short, visible light is here and FM radiowaves are much longer. So we’ve looked at the frequency, period and wavelength so far. Let’s finish with amplitude.
As waves travel, they create disturbance. The amplitude of a wave is the distance from the maximum disturbance to its undisturbed position. Think of a very flat sea… and then an incoming wave. The amplitude is the height of the top of the wave from the flat sea.
In another video we’ll be looking at the wave speed equation, and connecting wavelengths and frequencies: Wave Equation
For now you just need to know what these 4 keys words mean.
Frequency, period, wavelength, amplitude
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