3.7 use the above relationships in different contexts including sound waves and electromagnetic waves

okay so the 'above relationships' are wave speed = frequency x wavelength and frequency = 1 / time period

We just need to be able to substitute what we are given in questions into the equation. Here are some examples...

1- Find the speed of a wave of wavelength 12m and frequency 4Hz

To answer this, we use the equation wave speed = frequency x wavelength, so, 12 x 4 = 48. Therefore, the wave speed of this wave is 48 seconds. (NOTE: fyi, this is a really unrealistic wave speed, this is just an example of how to sub in the equation!)

2- A wave has a period of 0.35 seconds. Find the frequency of this wave.

For this question, we need to use the equation frequency = 1 / time period. We know the period is 0.35, so all we need to do is 1 / 0.35 = 2.857 which rounds to 2.86. so the frequency of this wave is 2.86Hz

3.9 understand that waves can be diffracted through gaps, and that the extent of diffraction depends on the wavelength and the physical dimension of the gap

The size of the gap relative to the size of the wavelength is also important...

3.8 understand that waves can be diffracted when they pass an edge

When a wave meets an obstacle, it could be reflected, refracted or diffracted.

If they are diffracted this just means that the edges of the waves 'bend' to get through gaps, this causes the waves to spread out and allows for waves to travel around corners.

The amount of diffraction depends on the size of the gap relative and the wavelength of the wave, the narrower the gap or the longer the wavelength, the more the wave spreads out

Here's what happens...

3.6 use the relationship between frequency and time period

frequency = 1 / time period


f = 1 / T 

(yes, its a capital T)

3.5 know and use the relationship between the speed, frequency and wavelength of a wave

wave speed = frequency x wavelength

In symbols: v = f x λ

3.4 understand that waves transfer energy without transferring matter

Waves carry/transfer every in the direction they're traveling in. For example, microwaves in an oven make things warm up. This is because they transfer heat energy to the food that is in the oven. However, microwaves do not transfer any particles or matter or anything to the food, just energy.

3.3 define amplitude, frequency, wavelength and period of a wave

Amplitude - this is the height of the wave (from rest to crest)

Frequency - the frequency is how many complete waves there are per second, it is measures in Hz (1 Hz is 1 wave per second)

Wavelength (λ)- this is the distance from one crest (or trough) to the other crest (or trough). It is represented in equations as lambda (λ)

Period (of a wave) - this is the time it takes for one complete wave to pass. It is measures in seconds (s)

3.2 understand the difference between longitudinal and transverse waves and describe experiments to show longitudinal and transverse waves in, for example, ropes, springs and water

Transverse (the uppy-downy ones)
Most waves are transverse (light waves and all waves of the electromagnet spectrum). In transverse waves the vibrations are at 90º to the direction energy is transferred by the wave

Longitudinal (the other ones)
Longitudinal waves include sound (and ultrasound) waves and shock waves (e.s. seismic waves). In longitudinal waves the vibrations are along the same direction as the energy transferred by the waves

If you have any spare time, it would be a great idea to watch this video, it is a little long but very helpful!...

https://youtu.be/jAXx0018QCc