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Practice questions · Harmful effects

Higher frequency, greater harm.

Six original Cambridge-style questions. They cover the hazard of each region, why the high-frequency end is the dangerous one, how people protect themselves, and the microwave misconception.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
The pattern behind the hazards

Heating at the low end. Cell damage at the high end.

01
[2 marks]

State a harmful effect on the body of:

(a) microwaves, [1] (b) infrared. [1]

(a) Internal heating of body cells (microwaves are absorbed by water in the tissue). ✓

(b) Skin burns from heating. ✓

02
[3 marks]

Sunlight contains ultraviolet radiation.

(a) State two harmful effects of ultraviolet on the body. [2] (b) State one way a person can reduce their exposure to ultraviolet. [1]

(a) Any two of: sunburn, premature ageing of the skin, skin cancer, eye damage. ✓✓

(b) Any one of: sunscreen, sunglasses, covering clothing, or limiting time in strong sun. ✓

03
[2 marks]

State the main harmful effect of X-rays and gamma rays on the cells of the body.

  • They can damage or mutate cells (including their DNA). ✓
  • This can cause cancer, and high doses can kill cells. ✓
04
Analysis
[2 marks]

Explain why, in general, the radiations at the high-frequency end of the electromagnetic spectrum are more harmful to the body than those at the low-frequency end.

  • Higher frequency means each wave carries more energy. ✓
  • That energy is enough to damage or mutate the molecules in cells, rather than just heating the tissue. ✓
05
Analysis
[2 marks]

A student claims that microwaves are dangerous in the same way as gamma rays, because both are "radiation". Explain why this comparison is misleading.

  • Microwaves have a much lower frequency and energy, so their main effect is heating tissue, not damaging cells. ✓
  • Gamma rays carry far more energy and can mutate or destroy cells, causing cancer, which microwaves do not do. ✓

Both are electromagnetic waves, but the energy they carry, and so the harm they cause, is very different.

06
Analysis
[3 marks]

A radiographer takes many X-ray images each day.

(a) Explain why repeated exposure to X-rays is a risk to the radiographer. [1] (b) State two precautions the radiographer can take to reduce their exposure. [2]

(a) X-rays can damage or mutate cells, and repeated exposure increases the total dose and so the risk of cancer. ✓

(b) Any two of: stand behind a lead or concrete screen, wear a lead apron, keep their distance, limit exposure time, and wear a badge to monitor their dose. ✓✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.