This large topic builds on your GCSE knowledge and includes many new area including interference and stationary waves.

An Introduction to Waves (and the Jelly baby Wave Machine)

You may remember most of this information from GCSE but this covers some of the wave properties you need to understand and introduces the jelly baby wave machine for the first time.

Wavelength, Period, Amplitude and Phase Difference

You must understand this key wave terminology to fully grasp this fascinating subject. Wavelength, time period, amplitude and phase difference are explained using jelly babies.

The Wave Equation

Very furry lambs and an analogy with train carriages explain the derivation of the important wave equation.

Reflection, Refraction, Diffraction and Polarisation 

Both transverse and longitudinal waves share similar properties that you must be familiar with to understand further topics like lenses and interference: but only transverse waves can be polarised.

The App running is called Ripple Free by Paul Falstad.

Amplitude and Intensity

This catches lots of people out. If you double the amplitude of a wave you give it four times as much energy, this leads on to the relationship between amplitude and intensity of a wave.

The Transverse Nature of EM Waves

EM waves are all around us from long wavelength radio waves to gamma radiation emitted from the rocks beneath your feet. 

Wavelengths and Frequencies of EM Waves

You should probably learn this! It is worth having a good idea of the wavelengths of the various parts of the EM Spectrum.

EM wave speed and refractive index 

A little bit about little c and how this is related to the refractive index of a material.

The Doppler Effect

The Doppler effect is caused by the relative motion between an object emitting waves and the observer. I have a go at recreating this effect myself and also show you some of the equations and why this effect is important in Physics

Polarisation of Waves

Only transverse waves can be polarised, this video explains why. It also shows why sunglasses are known as 'polaroids' and how you can test this yourself on a sunny day. 

Using Microwaves to Show Polarisation

This video shows how you can use a microwave transmitter and receiver to investigate the polarisation of microwaves. Plane polarised waves are emitted by the transmitter and If you measure the angle of the filter and record the intensity at the receiver you can then show Malus's Law in the lab.

Refraction and Snell's Law

You may recall that waves change speed when they pass from one medium into another - their frequency stays the same but their wavelength changes. This in turn cause a change in their direction as one side of the wavefront slows down or speeds up before the other.

Total Internal Reflection and Critical Angle

As light passes from a denser medium to an optically less dense substance there is a limit to the angle that the light can leave at. Beyond this critical angle the light doesn't leave and is totally internally reflected.

Refraction Extra Points 

A little bit extra on how as the wave speed changes this affects the wavelength and frequency of the wave.

Optical Fibres

Used in communications, and perhaps making it possible for you to read this webpage, optical fibres are used to send information at the speed of light around the world. They rely on light remaining inside the fibre due to total internal reflection.

Superposition of Waves

Waves can pass through other waves, like ripples on a pond, with their combined amplitude the sum of the individual dispacements at any one time - the principle of superposition.

Coherence and Path Difference

Coherent waves have a constant phase difference.

Coherence, path difference and phase difference are really important subjects to consider when we look at the interference of waves and how this leads onto double slit and diffraction grating patterns.

Phase and Phase Difference 

A little more about these two terms and why we measure the phase difference of a waves in degrees or radians.

Two Source Interference of Waves

Throw stones into a pond and the ripples pass through each other. The same effect of wave interference is also seen with sound, light, and microwaves.

Young's Double Slit Experiment

Everyone loves lasers in Physics. This shows how you can measure the wavelength of light in the lab.

Diffraction Gratings

If you shine light, or other types of EM radiation, through a series of small slits the waves interfere causing constructive interference at certain points. We can then use this method to calculate the wavelength of the light. It is also why DVDs and CDs make beautiful rainbows.

Velocity of Waves on a String

Hopefully you will have seen a slinky at school and observed a wave moving along it. The speed of a wave along a string really depends on the tension in the string and also the mass per unit length. Simple.

Standing Waves on a String

Waves transfer energy, right? Well they can, but they can also store energy and not go anywhere at all.

Stationary Waves on a String

Standing (or stationary) waves on strings are formed when a wave reflects from the fixed end of a string and then by superposition it combines to make points of maximum displacement (antinodes) and points of no-displacement (nodes).

Stationary Waves in an Open Tube

Stationary (or standing) waves can also form in a column of air which is the basis behind many musical instruments.

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