IGCSE Physics / The electromagnetic spectrum
Dangers of electromagnetic radiation and protection revision notes
Edexcel International GCSE Physics (4PH1), chapter 11: The electromagnetic spectrum, specification point 3.13. Free lesson.
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Too much electromagnetic radiation can harm the body, but each type causes a different kind of damage. Knowing the specific harm and how to reduce exposure helps you answer exam questions accurately.
What harm each type of wave causes
Different electromagnetic waves affect the body in different ways, so match each wave to its own harm. Microwaves heat body tissue from the inside, while infrared can burn the skin. Ultraviolet damages surface cells, causing sunburn and skin cancer. It can also damage the eyes and lead to blindness. Gamma rays and X-rays can cause cancer and mutations.
How ionising radiation can lead to cancer
Gamma rays and X-rays are the most dangerous because they are ionising. They pass deep into the body. Ionising radiation knocks electrons off atoms, making charged particles called ions. In cells, this can damage DNA, the instructions that control the cell. A change in DNA is called a mutation. A mutation can make a cell grow out of control, causing cancer. A large dose can kill cells outright.
How to reduce exposure and harm
Protection depends on the type of radiation. For gamma rays and X-rays, reducing exposure time, increasing distance and using shielding all lower the risk. Microwaves: a metal case and metal mesh in the oven door keep the waves inside. Infrared: keep a safe distance from strong heat sources and limit the time spent near them. Ultraviolet: use sunscreen and sunglasses, cover up or stay in the shade. Gamma rays and X-rays: use lead shielding, keep exposure times short and stay at a distance.
Answering questions about radiation risks
Use the exact harm linked to each wave. In a question about reducing exposure, give two clear actions. For X-rays, a radiographer can use lead shielding and increase distance or reduce the time spent near the source. For ultraviolet on the skin, state sunburn or skin cancer. For ultraviolet on the eyes, state eye damage or blindness. For protection from ultraviolet, give two measures such as sunscreen and sunglasses, or covering up and staying in the shade.