Wave Behaviour (Oxford AQA IGCSE Combined Science Double Award)

Wave Behaviour

• When a wave reaches a boundary between two materials, the wave may be:

  • Reflected

  • Transmitted

  • Absorbed

• A boundary is the surface at which two substances meet

• For example:

  • Air and water

  • Glass and air

  • Glass and water

• In reality, waves usually undergo a combination of reflection, transmission and absorption

Reflection

• Reflection occurs when:

A wave hits a boundary between two media and does not pass through, but instead stays in the original medium

• If the incident wavefronts are parallel to the boundary, then the wave will be reflected parallel to the boundary

Parallel reflection

• If the incident wavefronts hit the boundary at an angle, then the angle of incidence will be equal to the angle of reflection

Reflection at an angle

Transmission

• Transmission occurs when:

A wave passes through a substance

• For the process to count as transmission, the wave must pass through the material and emerge from the other side

• Refraction is a type of transmission

• When passing through a material, waves are usually partially absorbed

• The transmitted wave may have a lower amplitude because of some absorption

  • For example, sound waves are quieter after they pass through a wall

Transmission of a wave

Absorption

• Absorption occurs when:

Energy is transferred by the wave to the particles of a substance

• Waves can be partially or completely absorbed

  • Sound waves are absorbed by brick or concrete in houses

• If an object appears red, this means:

  • Only red light has been reflected

  • All the other frequencies of visible light have been absorbed

Absorption of light