radioactivity

Question 1

how should the scientist correct the count rate of the radioactive isotope for background radiation

Answer 1

subtract the background count rate

Question 2

what is an alpha particle

Answer 2

a helium nucleus

two protons and two neutrons

Question 3

which two types of radiation can be affected by a magnetic field

Answer 3

alpha
beta

Question 4

what is a beta particle

Answer 4

fast moving electrons produced when a neutron changes into a proton and an electron

Question 5

what is a gamma ray

Answer 5

an electromagnetic wave

Question 6

what is the charge of a gamma ray

Answer 6

0

Question 7

what is the charge of a beta particle

Answer 7

-1

Question 8

what is the penetrating power of an alpha particle

Answer 8

stopped by paper

Question 9

what is the penetration power of a beta particle

Answer 9

stopped by a few mm aluminium

Question 10

what is the penetration power of a gamma ray

Answer 10

gets stopped by a lot of cm of lead or many meters of concrete

Question 11

what happens to a particle when it is ionised

Answer 11

its number of electrons changes which gives it a charge

Question 12

what are the ionising powers of the three different types of radiation

Answer 12

alpha - most ionising
beta
gamma - least ionising

Question 13

what happens to the mass and proton numbers during gamma decay

Answer 13

they remain the same, the process just makes the nucleus less energetic

Question 14

what is a sievert

Answer 14

the amount of radiation received by a person (the dose)

Question 15

IN WHAT TWO WAYS CAN RADIATION BE MEASURED AND DETECTED

Answer 15

using a photographic film or a geiger-muller tube

Question 16

how does photographic film show radiation

Answer 16

it becomes darker as it absorbs radiation

the darker it is, the more radiation it has absorbed

Question 17

how is photographic film used in real life situations

Answer 17

people who work with radiation such as radiographers wear film badges which are checked regularly to monitor levels of radiation absorbed

to get an accurate measure of the dose received, the badge contains different materials that the radiation must penetrate in order to reach the film

Question 18

how does a geiger-muller tube measure radiation

Answer 18

each time it absorbs radiation, it transmits an electrical pulse to a counting machine which makes a clicking sound or displays the COUNT RATE

Question 19

how does distance from a radioactive object affect the amount of radiation present

Answer 19

it decreases with distance because the waves spread out

Question 20

natural sources of radiation

Answer 20

• rocks and building materials
• cosmic rays from space
• foods

Question 21

man made sources of radiation

Answer 21

• medical sources
• nuclear waste/accidents

Question 22

what percentage of activity would a radioactive source be at after two half lives

Answer 22

25% (halving twice 100 - 50 then 50 - 25)