3.4.1
Reflection & Absorption
Test your knowledge with free interactive questions on Seneca — used by over 10 million students.
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.

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.
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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.
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Jump to other topics
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Practice questions on Reflection & Absorption
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Which of these are true of waves at a boundary?True / false
- 2
- 3When a wave is transmitted, it is often also:Multiple choice
- 4
- 5What type of material absorbs the most light?Multiple choice
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