Practice Question

1.Which types of electromagnetic waves are most harmful

The shorter the wavelength, greater energy of the EM waves, the more harmful they are. Ultraviolet, X-rays and gamma rays are ionising forms of radiation.

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

Ionising radiation has enough energy to knock electrons off of atoms to form ions. 

3. Describe how UV radiation is harmful to us

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. 

4. Describe how X-rays are harmful to us

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.

5. Describe how Gamma rays are harmful to us

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.

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.

100mSv is a reasonably large dose. However, this is over a 6 month period which is less than 17mSv per month. So, this is still a small dose, but higher than a normal background dose due to radiation.