- How does a force that is proportional to displacement result in an oscillation?
- Are all oscillations simple harmonic?
- What is the connection between oscillations and waves?
- Are waves really made of an infinite number of wavelets?

### The simple pendulum

It may be called the simple pendulum but deriving the equation for its motion isn't easy. In the simple treatment the forces are balanced at the bottom but this isn't really true. Examiners like to see if you realise this.

### Wave basics

Wave quantities wave propagation reflection refraction interference diffraction

### Waves in a string

It is easy to observe the wave motion in a string but it doesn´t tell the whole story of wave properties. A string wave can't diffract or interfere. Sometimes simple explanations cause misunderstandings. Here a string wave is polarised by a narrow slit.

### Light

To understand the propagation of electromagnetic waves you need to have studied the next section on electromagnetism. However it is enough to use what we know about other waves to understand the wave nature of light.

### Mass on a spring

Another physics book classic, the mass hanging on a spring. A bit easier to analyse than a pendulum but not as easy as the mass on a spring in space. Quite obvious that the acceleration is proportional to displacement, once you realise that SHM follows.

### Wave properties

Wave simulations use the same mathematical equations that are used to model real waves so have the same properties. Here a ripple tank simulation will be used to show how waves reflect, refract, interfere and diffract.