Light

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Waves at a Boundary

When waves travel from one medium to another, their speed and wavelength change but their frequency stays the same.

Speed and wavelength change

The speed of a wave changes when it travels from one medium to another.
The wavelength of a wave also changes when it travels from one medium to another.
The speed and the wavelength are directly proportional:
- If the speed doubles, the wavelength doubles.
- If the speed halves, the wavelength halves.

Frequency is unchanged

The frequency of the wave does not change because the source is producing the same number of oscillations (vibrations) per second.

Waves at a Boundary

Waves can be reflected, refracted, absorbed and transmitted (passes through) at the boundary between one medium (material) and another. The way in which these processes happen varies with wavelength.

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Refraction

A wave’s speed can change when moving from one medium to another.
If the wave crosses to the new medium at an angle (not 90 degrees), the change in the wave’s speed will cause the direction of the wave’s motion to change and the wave will appear to bend.
This is called refraction.

Reflection

Reflection happens when a wave hits a flat surface (plane) and bounces off.

Absorption

When waves meet some materials, the energy is absorbed by the material.
For example, when light falls on a matt black surface, most of the energy is absorbed.

Transmission

Waves carry on travelling through a new material.
This often leads to refraction.

1Biology

1.1Practicals

1.1.1Microscope & Bacteria

1.1.2Bacteria

1.1.3Osmosis Tests

1.1.4Osmosis & Food Tests

1.1.5Enzymes

1.1.6Enzymes 2

1.1.7Photosynthesis & Plant Responses

1.1.8Photosynthesis Experiments

1.1.9Reaction Time

1.1.10Quadrats

1.1.11Decay

2Chemistry

2.1Practicals

2.1.1Salts

2.1.2Neutralisation

2.1.3Titration

2.1.4Electrolysis

2.1.5Electrolysis 2

2.1.6Rate of Reaction

2.1.7Rate of Reaction 2

2.1.8Chromatography

2.1.9Identifying Gases

2.1.10Identifying Gases 2

2.1.11Identifying Ions

2.1.12Carbonates, Halides & Sulfates

2.1.13Flame Emission Spectroscopy

2.1.14Water Purification

2.1.15Water Purification 2

3Physics

3.1Practicals

3.1.1Specific Heat Capacity

3.1.2Thermal Capacity & Insulation

3.1.3Latent Heat

3.1.4Resistance & Current

3.1.5Resistance & Current 2

3.1.6Density

3.1.7Density 2

3.1.8Force & Extension - Springs

3.1.9Waves - Ripple Tank

3.1.10Light

3.1.11Light Reflection & Refraction

3.1.12Radiation

3.1.13Radiation 2

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