Dangers of Electromagnetic Waves
Learn Dangers of Electromagnetic Waves for GCSE Physics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Ultraviolet, X-rays and gamma rays can damage living cells, and the risk depends on the radiation dose received.
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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.
Topic overview
Electromagnetic waves can have hazardous effects, particularly on human tissue. The effect depends on the type of wave and on the size of the dose.
Ultraviolet waves can cause skin to age prematurely and increase the risk of skin cancer. X-rays and gamma rays are ionising radiation, which means they can knock electrons off atoms, and this can cause gene mutation or cell destruction leading to cancer.
Radiation dose measures the risk of harm from exposure and is measured in sieverts. Because 1 sievert is a very large dose, millisieverts are usually used, with 1000 mSv equal to 1 Sv. The higher the frequency of the wave, the greater the energy and generally the greater the hazard.
Revision notes
Ultraviolet
Ultraviolet waves can cause skin to age prematurely.
They also increase the risk of skin cancer. This is why sun cream is used to absorb ultraviolet before it reaches the skin.
Ionising radiation
X-rays and gamma rays are ionising radiation, meaning they can knock electrons off atoms.
This can cause gene mutation or cell destruction, which can lead to cancer. They carry the highest energies in the spectrum, which is why they are the most hazardous.
Radiation dose
Radiation dose measures the risk of harm resulting from exposure of the body to radiation.
It is measured in sieverts, and because 1 sievert is a very large dose, millisieverts are usually used: 1000 mSv = 1 Sv.
Key points
- Ultraviolet causes premature skin ageing.
- Ultraviolet increases the risk of skin cancer.
- X-rays and gamma rays are ionising.
- Ionising radiation can cause gene mutation.
- Dose is measured in sieverts.
- 1000 millisieverts equal 1 sievert.
Worked examples
Example 1
State two harmful effects of ultraviolet radiation on the skin. [2 marks]
Model answer
It can cause the skin to age prematurely (1 mark), and it increases the risk of skin cancer (1 mark).
Example 2
Explain what is meant by ionising radiation and why it is hazardous. [3 marks]
Model answer
Ionising radiation can knock electrons off atoms (1 mark). This can cause gene mutation within cells (1 mark), or destroy cells altogether, which can lead to cancer (1 mark).
Example 3
Convert a dose of 0.5 sieverts into millisieverts. [2 marks]
Model answer
1 sievert = 1000 millisieverts (1 mark), so 0.5 × 1000 = 500 mSv (1 mark).
Common mistakes
Saying all electromagnetic waves are equally hazardous.
The hazard generally increases with frequency and energy.
Saying radio waves are ionising.
Only X-rays and gamma rays are ionising in the specification.
Giving dose in becquerels.
Becquerels measure activity; sieverts measure dose.
Not explaining what ionising means.
It means knocking electrons off atoms, which is the source of the hazard.
Exam tips
- Define ionising as knocking electrons off atoms.
- Link the hazard to gene mutation or cell destruction.
- Use sieverts and millisieverts correctly.
- Note that hazard generally increases with frequency.
Key terms
- Ionising radiation
- Radiation able to knock electrons off atoms.
- Gene mutation
- A change to DNA that can lead to cancer.
- Sievert
- The unit of radiation dose.
- Millisievert
- One thousandth of a sievert.
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Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.