Uses of radiation

Question 1

Smoke detectors use [ ] radiation, how? (3 steps)

Answer 1

Alpha

1. A weak source of alpha radiation is placed in the detector close to 2 electrodes
2. The source causes ionisation, and a current flows between he electrodes
3. If there is a fire then the smoke will absorb the radiation, so the current stops and the alarm sounds

Question 2

Tracers in medicine always have [ ] half life beta or [ ] emitters

Answer 2

short

gamma

Question 3

How are radioactive isotopes used as tracers?

Answer 3

They’re injected/ swallowed by patients and their progress around the body is monitored using an external detecor

Question 4

Give an example of an isotope that is used to test the thyroid gland

Answer 4

Iodine-131

Tests whether the gland is taking in iodine as it should

Question 5

Radiotherapy uses [ ]

Answer 5

Gamma rays

Question 6

What 2 things have to be checked when using gamma radiation to kill cancer cells?, why?

Answer 6

Right dosage and directed carefully. High doses of Gamma rays will kill all living cells, you don’t want to kill normal cells.

Question 7

Food can be exposed to [ ] doses of [ ] which will kill all microbes, keepeing the food [ ] for longer

Answer 7

high
gamma rays
fresher

Question 8

Medical instruments can be [ ] by gamma rays

Answer 8

sterilised

Question 9

State an advantage of irradiation over boiling

Answer 9

Doesn’t involve high temps so things like apples and plastic can be sterilised without damage
food isn’t radioactive afterwards

Question 10

The isotope used for irradiation (sterilisation) needs to be a very strong [ ] emitter of gamma rays with a reasonably [ ] half-life (at least several [ ]) so that it doesn’t need replacing too often.

Answer 10

strong
long
months