Uses and penetrating power of radiation

Question 1

Types of nuclear radiation:
Composition:
Atomic mass:
Relative charge:

Answer 1

Alpha - helium nucleus 2p 2n, 4, 2
Beta - electron 0p 0n, negligible, -1
Gamma - EM photons short wavelength high frequency, 0, 0

Question 2

Test for the type of radiation a source is emitting

Answer 2

measure the count rate at a fixed distance then place a sheet of paper and then aluminium to see how it affects the count rate

Question 3

Three traits of alpha radiation

Answer 3

most absorbing
least penetrating
highly ionising
slow moving

Question 4

Alpha radiation range in air

Answer 4

2-10cm in air

Question 5

What is alpha radiation absorbed/stopped by

Answer 5

hand, paper, thin metal foil

Question 6

Uses of alpha radiation

Answer 6

smoke alarms - quickly ionise atoms then lose energy so allow current to flow and don’t travel far

Question 7

Tracks from a alpha source are

Answer 7

the same length as the same kinetic energy

varies between sources

Question 8

Two traits of beta radiation

Answer 8

weakly ionising

fast moving

Question 9

Range of beta radiation in air

Answer 9

up to a metre

Question 10

Beta radiation is absorbed/stopped by

Answer 10

a few mm of aluminium

Question 11

Beta radiation can penetrate

Answer 11

air, hand, paper

Question 12

Beta radiation uses

Answer 12

detecting/controlling the thickness of materials

Question 13

Positron range in air

Answer 13

virtually zero as are annihilated by electrons

Question 14

Faster beta particles travel further in air because

Answer 14

they have a greater initial kinetic energy

Question 15

Tracks from a beta source vary because

Answer 15

the range of initial kinetic energies up to a maximum

Question 16

Three traits of gamma radiation

Answer 16

very weakly ionising
travels at the speed of light
chargeless
massless

Question 17

Gamma radiation range in air

Answer 17

infinite

Question 18

Gamma radiation is absorbed/stopped by

Answer 18

lead, concrete

Question 19

Gamma radiation can penetrate

Answer 19

hand, paper, most through aluminium

Question 20

Uses of gamma radiation

Answer 20

tracers for medical imaging -

treatment for cancer

Sterilising medical instruments

Question 21

Gamma intensity laws and equation

Answer 21

Radiation spreads out in all directions therefore intensity decreases in inverse square relationship with distance from the source

I = k/x^2

Question 22

Points on radioactive diagnosis

Answer 22

short half life to reduce exposure and damage while long enough for accurate diagnosis/image or to obtain the required information before it decays- detected by a PET scanner

dose recieved is medically insignificant

must emit gamma rays with sufficient energy to escape the body

Question 23

Why is technetium-99m used for radioactive tracers

Answer 23

6 hour half life - stable enough for the measurements to be made and short enough to decay quickly after use

gamma emitter not beta so low radiation dose to patient

99m means it is metastable = between excited and stable = long-lived excited state = safer

Question 24

Knowledge about half lives can be used for

Answer 24

carbon/argon dating

Question 25

long half lives are useful in… but are bad in…so must…

Answer 25

nuclear power

waste products as dangerous so must plan ahead for storage i.e. seal underground.