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AQA GCSE · Question 06.3 · Waves
Explain why exposure to gamma rays can be harmful but exposure to radio waves is not harmful.
Explain why exposure to gamma rays can be harmful but exposure to radio waves is not harmful.
How to approach this question
1. Relate the danger of an EM wave to one of its properties (frequency, wavelength, or energy).
2. What is the key difference between high-energy EM waves (like gamma) and low-energy ones (like radio)? Use the term "ionising".
3. Explain what "ionising" means in terms of what it does to cells.
Full Answer
Gamma rays have a very high frequency and therefore high energy. They are a form of ionising radiation, which means they can knock electrons out of atoms and molecules, damaging cells and DNA, which can lead to mutations or cancer. Radio waves have a very low frequency and low energy, so they are non-ionising and do not cause this type of damage.
The potential for harm from electromagnetic radiation is determined by the energy carried by the waves, which is directly proportional to their frequency.
- **Gamma Rays:** These are at the high-frequency, high-energy end of the EM spectrum. They have enough energy to be **ionising radiation**. This means they can strip electrons from atoms or molecules in body tissues. This ionisation can damage or destroy cells, or mutate DNA, which can lead to cancer.
- **Radio Waves:** These are at the low-frequency, low-energy end of the spectrum. They do not have enough energy to ionise atoms. They are **non-ionising** and pass through the body without causing cellular damage.
Common mistakes
✗ Just saying "gamma rays are stronger" without mentioning frequency, energy, or ionisation.\n✗ Confusing the properties, e.g., saying radio waves have high frequency.\n✗ Not explaining what ionising radiation does.
Practice the full AQA GCSE Physics Higher Tier Paper 2
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