Radioactivity

Question 1

How does ionising radiation work?

Answer 1

ionise atoms by removing electrons

Question 2

What is an alpha particle?

Answer 2

a helium nucleus

Question 3

What is the charge of an alpha particle?

Answer 3

+2e

Question 4

What is the range of alpha in air?

Answer 4

1-2cm

Question 5

What can alpha be stopped by?

Answer 5

sheet of paper

Question 6

What is beta minus?

Answer 6

an electron

Question 7

What is the charge of beta minus?

Answer 7

-e

Question 8

What is the range of beta minus in air?

Answer 8

1-2m

Question 9

What can beta minus be stopped by?

Answer 9

1-3mm of aluminium

Question 10

What is beta plus?

Answer 10

a positron

Question 11

What is the charge of beta plus?

Answer 11

+e

Question 12

How far can beta plus travel in air?

Answer 12

not very as positrons get annihilated by electrons

Question 13

What is gamma radiation?

Answer 13

EM wave

Question 14

What is the range of gamma in air?

Answer 14

kilometers

Question 15

What can gamma photons be stopped by?

Answer 15

few cm of lead

Question 16

Which form of radiation is the most ionising?

Answer 16

alpha

Question 17

Which type of radiation is the least ionising?

Answer 17

gamma

Question 18

How does an unstable nucleus with more than 82 protons decay?

Answer 18

alpha- emitting a helium nucleus

Question 19

What is emitted in beta minus decay?

Answer 19

an electron

Question 20

What is emitted in beta plus decay?

Answer 20

a positron

Question 21

What is emitted in gamma decay?

Answer 21

surplus energy- gamma photon

Question 22

Define radioactivity:

Answer 22

random decay of an unstable nuclei

Question 23

Define half life:

Answer 23

time taken for half the number of active nuclei in a sample to decay

Question 24

Define activity:

Answer 24

rate of nuclei decay

Question 25

What is decay constant?

Answer 25

probability of decay of an individual nucleus per unit time

Question 26

What is 'N' representative of in the nuclear decay equation?

Answer 26

number of undecayed nuclei left in the source at time t

Question 27

What is the relationship between decay constant and half life?

Answer 27

inversely proportional

Question 28

What is carbon dating used for?

Answer 28

determining the age of organic materials

Question 29

Which isotopes have a constant ratio?

Answer 29

carbon 12 and carbon 14

Question 30

What happens to a living thing once it dies?

Answer 30

stops taking in carbon so the carbon 14 nuclei within the dead material decreases exponentially with time

Question 31

How can the age of a dead material be determined?

Answer 31

by comparing the carbon 12 to carbon 14 ratio of the dead thing with the same type of living thing

Question 32

Why can the C12 to C14 ratio not be assumed to remain constant?

Answer 32

it is affected by natural events such as volcanic eruptions as well as increased emissions from cars and burning fossil fuels

Question 33

Why is there large uncertainty when aging a relic? eg rocks

Answer 33

the value of the ratio in the past is not known