Half Life

Question 1

Half Life

Answer 1

the average time taken for half the number of atoms to decay.

Question 2

why does the intensity of radiation decrease over time?

Answer 2

The number of unstable (radioactive) nuclides decrease as they stabilize.

Question 3

what are the 7 uses of isotopes?

Answer 3

1. Detecting thickness of paper.(beta particles)(long H-L)
2. Tracing in medicine.(Gamma rays)(Short H-L)
3. Tracing in agriculture. (Gamma rays)(Short H-L)
4. Tracing in industry.(Gamma rays)(Short H-L)
5. Radiotherepy.(Gamma rays)
6. Sterlization.(Gamma rays)
7. Archaeology.

Question 4

A radioactive sample of half life 3 hours and initial activity 720 count/min when will the activity be 45 count/min?

Answer 4

4 half lives, each half life is 3 hours so we need 12 hours.

Question 5

unit

Answer 5

count/min

Question 6

How to get the corrected(pure) radiation?

Answer 6

Total original number-background radiations=pure radiation.

Question 7

what do u do if asked to get the remained atoms?

Answer 7

=number after applying the given half-lives.

Question 8

what do u do if asked to get the decayed atoms?

Answer 8

=original number-number after applying the given half-lives.

Question 9

what do u do if given background radiation and asking for the total after number of half-lives?

Answer 9

• subtract the b.g radiation from the total number.
• calculate after the half lives.
• add the b.g radiation.

Question 10

what are some economic or environmental issues involved in the storage of radioactive materials with very long half-lives.

Answer 10

Economic:
1.reduction in tourism.
2.loss of farming land.
Environmental:
1.leakage into water.
2.crop mutation.

Question 11

state some precautions to be taken when radioactive isotopes are used?

Answer 11

1. hold with long tongs.
2. wear protection like (gloves, googles, etc.)
3. limit exposure time.

Question 12

where should radioactive sources with long half-lives be stored?

Answer 12

in thick lead containers and buried under ground.