AQA GCSE Harmful Electromagnetic Waves

AQA GCSE Harmful Electromagnetic Waves(Physics)

Harmful EM Waves

Some types of Electromagnetic waves can cause us harm, or be hazardous to our health. The effects of the radiation depend on the type of radiation and the size of the dose.

Ionising radiation

Ultraviolet, X-rays and Gamma rays are all forms of ionising radiation. This means that they have enough energy to knock electrons off of atoms to form ions.

This is shown in the diagram below.

Harmful effects of Ultraviolet Radiation

1. Short term exposure to Ultraviolet radiation can cause sunburn and ageing of the skin.

2. Long term exposure to ultraviolet radiation can cause mutations (changes) to DNA, which increases the risk of developing skin cancer.

3. Ultraviolet radiation can damage the retina at the back of our eyes.

We should use sunscreen over the surface of our skin to protect our skin from harmful UV radiation. Sun glasses can absorb harmful UV radiation which will help to protect our eyes.

Harmful effects of X-Rays

X-rays are ionising forms of radiation, so when our bodies are exposed to X-rays there is a slight increase risk of cancer. However, the risk is tiny.

This is because as the X-rays penetrate the body, they can damage the DNA in the cells.

Many people have X-rays for dental work, or for doctors to check for bone fractures. The benefits of the X-ray will often outweigh the risks. The dosage of X-rays from the X-ray machine is tiny, so the risk is very small.

Harmful effects of Gamma Rays.

Gamma rays are ionising forms of radiation, these also carry the most amount of energy of all the electromagnetic waves.

Gamma rays are highly penetrating, so they easily pass through the human body.

Gamma rays are used by doctors to kill cancer cells, this is known as radiotherapy. However, gamma rays can also harm, or kill healthy cells. After radiotherapy many patients have radiation sickness due to exposure of gamma rays.

When healthy cells are exposed to gamma rays, the gamma rays can cause DNA mutations, which can increase the chance of cancer.

Dosage of Radiation.

Sieverts is a measure of radiation dose to indicate the risk of harm resulting from an exposure of the body to the radiation.

1 sievert (Sv) = 1000 millisieverts (mSv). 1 Sievert is a very large dose, so most exposures are based on millisieverts as shown in the table below.

Activity	Radiation dose in millisieverts (mSv)
Chest X ray	0.1
Typical annual background radiation	2.4
Flight from London to New York	0.05
Dental X ray	0.005

Practice Question

1.Which types of electromagnetic waves are most harmful

2.If radiation is ionising, what does this mean?

3. Describe how UV radiation is harmful to us

4. Describe how X-rays are harmful to us

5. Describe how Gamma rays are harmful to us

6. An astronaught mission in space will mean that the astronaughts will be exposed to 100mSv over a 6 month period. Evaluate if the astronaughts should be concerned about their exposure to radiation during their mission.