P2.5 Radioactive Substances

Question 1

Is the effect of beta/gamma the same inside the body as out?

Answer 1

Yes

Question 2

Effects of beta/gamma inside and outside the body

Answer 2

Dangerous, reaches cells throughout the body

Question 3

Effect of alpha outside the body

Answer 3

• Some danger
• Can be absorbed by skin
• Can damage skin cells

Question 4

Effect of alpha inside the body

Answer 4

Very dangerous, affects surrounding tissue

Question 5

4 sources of background radiation

Answer 5

Cosmic rays
Food/Drink
Air travel
Medical (X-Rays)

Question 6

Define ‘half-life’

Answer 6

Time taken for the number of nuclei of the isotope in a sample to halve

Question 7

Give 3 uses of radiation

Answer 7

ANY FROM

Sterilising medical instruments, smoke detectors, killing cancer cells, chemical tracers

Question 8

Why are medical/chemical tracers safe to use?

Answer 8

Not poisonous

Short half-life, decays before damage

Question 9

What type of radiation is used for medical tracers? Why?

Answer 9

Gamma and beta; alpha can’t pass through skin

Question 10

The patient drinks water containing a tiny amount of the radioactive substance. True or False?

Answer 10

True

Question 11

A detector graph goes up then slants back down. What does this tell you?

Answer 11

Radioactive substance has gone in and out of the healthy kidney

Question 12

What would happen to a radioactive substance put through a blocked kidney?

Answer 12

It would go in but wouldn’t come back out

Question 13

What would the detector graph show for a blocked kidney?

Answer 13

The graph would go up and not come back down
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|/\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Question 14

3 ways to limit exposure to radiation

Answer 14

Step AWAY from the source (long handles)
Limit TIME with ‘at risk’ (of radiation) areas
Thick concrete BARRIERS/thick lead plates (shield)

Question 15

What did Rutherford and Marsden find out about the nucleus?

Answer 15

• Positive, it repels alpha

- Much smaller than an atom; because most alpha not deflected

Question 16

What charge does gamma have?

Answer 16

No charge, it’s an EM wave

Question 17

If you have a magnetic field and aim a beam of light through it, what would the results look like? Explain the result of beta. (Separating radiation)

Answer 17

• Gamma would go straight through
• Alpha would deflect at a small angle
• Beta would deflect in the opposite direction at a larger angle BECAUSE IT’S OPPOSITELY CHARGED AND LIGHTER

Question 18

How does uranium dating work?

Answer 18

Radioactive uranium in igneous rocks has a very long half life. Each U atom days into an atom of Pb.

Question 19

How does carbon dating work?

Answer 19

Living wood contains a tiny proportion of radioactive carbon with a long half life. The amount of C in a dead tree decreases.

Question 20

What is a radioactive substance?

Answer 20

A substance that gives off radiation from the nuclei of its atoms all the time

Question 21

In every half life, what decreases by half?

Answer 21

The number of atoms of a radioactive isotope and the activity

Question 22

What is the activity of a radioactive source?

Answer 22

The number of nuclei that decay per second

Question 23

“Radioactive decay is a random process.” Yes or No? If not, why?

Answer 23

Yes, it’s random