P1bL3 Dangers of Radiation

Key Words

Dose - how much radiation is absorbed.

Gamma rays - very energetic (very short wave) electromagnetic radiation from nuclei.

High energy - lots of energy (really?)

High energy radiation - EM waves of short wavelength carry a lot of energy.

Infra red radiation - radiation given out by warm objects with slightly longer wavelength than visible red light.

Ionising - knocks electrons off atoms.

Malignant - a cancer that spreads.

Microwaves - radio waves of wavelength 10 cm or less.

Mutation - change in genetic material.

Tumour - cancerous growth.

Ultra-violet - short wavelength light, with wavelength slightly shorter than visible violet light.

Visible light - light of a wavelength our eyes can detect.

X-rays - short wavelength radiation less energetic than gamma rays, but more energetic than ultraviolet.

Grade E

Electromagnetic waves can be harmful:

• Microwaves can cause deep burns by vibrating water molecules in out tissues.  The door of a microwave oven is screened to stop them escaping.
• Infra red can burn us.
• Ultraviolet from the sun forms Vitamin D, but too much exposure can burn our skins.  It can even cause skin cancer.
• Radiographers who use X-rays have to stand behind a lead-glass screen and wear a lead apron to reduce the dose to which the are exposed.
• Gamma ray equipment is kept behind thick concrete walls.

Grade C

Visible light does not harm us as such, but if too bright, the retina will be damaged.  That's why it's important not to stare into a laser.

UV light causes cells below the skin to die, and too much exposure makes the skin look old and wrinkly.  Skin cancer can result from mutations caused by UV light.  The dark pigment released due to sun bathing is called melanin and helps to protect us.  The ozone layer cuts down the harmful radiation.  While ozone (O3) is a nasty pollutant on the ground, the thinning of the ozone layer could cause a large increase in the rate of skin cancers.

X-rays pass through soft tissues and are stopped by bones.  They can cause cell damage if not properly controlled. Up to about forty years ago, shoe shops had X-ray machines into which you could put a coin in a slot.  You could then see X-ray pictures of your feet in their shoes.

Gamma rays are given out by the nuclei of decaying atoms.  When a nucleus undergoes radioactive decay, there is a lot of energy.  This high energy is turned into gamma rays.  Nuclear power station reactors need thick concrete shields to protect us against gamma radiation.

Grade A

When high energy radiations interact with matter, electrons are knocked off the atoms.  This is why UV, X-rays, and gamma rays are referred to as ionising radiation.  This process can seriously damage or kill living cells.  Damage to genetic material can cause a mutation which can go on to cause the cells to divide in an uncontrolled way.  A tumour then grows.  If it spreads about the body, it is malignant, and this will result in death.

The key thing is the dose which depends on:

• The intensity of the radiation;

• The time of exposure.

People working with radiation are monitored carefully to ensure that they do not receive too big a dose.