[9] Radioactivity Flashcards Preview

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Flashcards in [9] Radioactivity Deck (11):
1

What is background activity?

Background activity is radiation that is always a constant. It is emitted from our surroundings, walls, rocks, people. It is naturally occurring.

2

Sources of Background Radiation

Cosmic
Terrestrial
Dietary
Medical
Consumer products
Radon
Other

3

How can the background count be measured?

Using a Geiger Muller Tube and Scalar counter

4

Describe the process of ionisation due to radioactive substances emitting ionising radiations (Alpha, Beta, Gamma)

During ionisation an electron or electrons are knocked off atoms or molecules so that they have become positively charged.

5

Order the three types of ionising radiation in terms of penetrating distance from smallest to largest.

Alpha
Beta
Gamma

6

Order the three types of ionising radiation in terms of ionising potential from highly ionising to weakly ionising.

Alpha
Beta
Gamma

7

Order the three types of ionising radiation in terms of relative atomic size from smallest to largest.

Gamma
Beta
Alpha

8

Uses of radioactivity in industry

Thickness gauge - If a radioisotope is placed on one side of a moving sheet of material and a GM tube on the other, the count-rate decreases if the thickness increases. This technique is used to control automatically the thickness of paper, plastic and metal sheets during manufacture.

• Sterilisation of products
• Electricity generation

Radioactive tracers - The progress of a small amount of a weak radioisotope injected into a system can be 'traced' by a GM tube or other detector. The method is used in industry to measure fluid flow in pipes

9

Uses of radioactivity in medicine

Radioactive tracers - The progress of a small amount of a weak radioisotope injected into a system can be 'traced' by a GM tube or other detector. The method is used in medicine to detect brain tumours.

Radiotherapy - Gamma rays from strong cobalt radioisotopes are replacing X-Rays in the treatment of cancer.

Sterilisation - Gamma rays are used to sterilise medical instruments by killing bacteria.

• Treatment of cancerous tumours

10

Uses of radioactivity in agriculture

Radioactive tracers - The progress of a small amount of a weak radioisotope injected into a system can be 'traced' by a GM tube or other detector. The method is used in agriculture to study the uptake of fertiliser by plants.

Sterilisation - Gamma rays are used to 'irradiate' some foods, again killing bacteria to preserve the food for longer.

• Improve food crops
• Control insect pests
• Measure soil moisture content
• Measure erosion rates
• Salinity

11

During the fusion reaction some mass is converted to energy

E = MC^(Squared)