Properties of Electromagnetic Waves
Build confidence in Properties of Electromagnetic Waves for GCSE Physics with this free worksheet and full mark scheme — Higher-tier exam-style questions with worked answers for AQA, Edexcel and OCR. Electromagnetic waves refract at boundaries because they change speed, which can be shown using wavefront diagrams.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
This is a Higher tier only topic, so there's no Foundation paper — only the Higher worksheet and mark scheme below.
Topic overview
Electromagnetic waves are generated by changes in atoms and in the nuclei of atoms. This is a Higher-only topic.
Gamma rays originate from changes in the nucleus of an atom. Other electromagnetic waves originate from changes in the arrangement of electrons within atoms, or from oscillations in electrical circuits.
Electromagnetic waves may be reflected, refracted, transmitted or absorbed at a boundary. What happens depends on the wavelength of the wave and on the properties of the materials. Radio waves can be produced by oscillations in electrical circuits, and when they are absorbed by a conductor they may create an alternating current of the same frequency.
Revision notes
Where they come from
Gamma rays originate from changes in the nucleus of an atom.
Other electromagnetic waves originate from changes in the arrangement of electrons within atoms, or from oscillations in electrical circuits.
Behaviour at a boundary
Electromagnetic waves may be reflected, refracted, transmitted or absorbed when they meet a boundary.
Which occurs depends on the wavelength of the wave and on the properties of the two materials. Refraction is caused by the change in wave speed at the boundary.
Radio waves and circuits
Radio waves can be produced by oscillations in electrical circuits.
When radio waves are absorbed by a conductor, they may create an alternating current with the same frequency as the wave itself. This is how radio receivers work.
Key points
- Gamma rays come from changes in the nucleus.
- Other EM waves come from changes in electron arrangement.
- Radio waves come from oscillations in circuits.
- EM waves may be reflected, refracted, transmitted or absorbed.
- What happens depends on wavelength and materials.
- Absorbed radio waves can create an alternating current.
Worked examples
Example 1
State where gamma rays originate. [1 mark]
Model answer
From changes in the nucleus of an atom (1 mark).
Example 2
Explain what may happen when an electromagnetic wave meets a boundary between two materials. [3 marks]
Model answer
The wave may be reflected or refracted at the boundary (1 mark). It may also be transmitted through the second material or absorbed by it (1 mark). Which of these occurs depends on the wavelength of the wave and on the properties of the two materials (1 mark).
Example 3
Explain how radio waves can produce an alternating current in a receiver. [2 marks]
Model answer
The radio waves are absorbed by a conductor in the receiver (1 mark), creating an alternating current with the same frequency as the radio wave itself (1 mark).
Common mistakes
Saying all EM waves come from the nucleus.
Only gamma rays do; the others come from electron changes or circuit oscillations.
Forgetting that behaviour depends on wavelength.
Both the wavelength and the material properties determine what happens.
Saying absorbed radio waves produce direct current.
They produce an alternating current of the same frequency.
Confusing gamma rays and X-rays by origin.
Gamma comes from the nucleus; X-rays come from electron changes.
Exam tips
- Distinguish gamma rays by their nuclear origin.
- Name all four possible behaviours at a boundary.
- Say alternating current with the same frequency for radio receivers.
- Remember this is a Higher-only topic.
Key terms
- Nucleus
- The source of gamma rays.
- Oscillation
- A repeated back-and-forth motion, producing radio waves.
- Boundary
- The interface where reflection or refraction occurs.
- Alternating current
- Current produced when radio waves are absorbed.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.