physics

Question 1

what are the 3 types of radiation

Answer 1

alpha, beta, gamma

Question 2

what is the charge of alpha

Answer 2

2 neutrons
2 protons
(+2)

Question 3

What is radioactive decay

Answer 3

A neucleus emitting radiation to make it more stable

Question 4

What is beta radiation, and how is it produced

Answer 4

single electron
produced in nuclei when a neutron changes into a proton and an electron

Question 5

What is gamma radiation

Answer 5

gamma radiation is an electromagnetic wave

Question 6

How do these radiations penatrate and ionise differently

Answer 6

Alpha - least penetrative (stopped by a peice of paper)
->very ionising (highest mass and charge)
Beta - goes through paper, but stopped by thin aluminium
->ionising
Gamma - can only be partially stopped by lead (goes through rest)
->weakly ionising

Question 7

When an alpha particle in emmited, how does it affect the mass number and atomic number

Answer 7

mass number +4
atomic number +2

Question 8

When an beta particle in emmited, how does it affect the mass number and atomic number

Answer 8

mass number stays the same
atomic number +1

Question 9

WHat neucleus does an alpha particle have?

Answer 9

Helium

Question 10

What is th mass of an alpha particle

Answer 10

4 x the mass of neucleon

Question 11

what is the mass of a beta particle

Answer 11

1/2000 mass of a proton

Question 12

Whats the mass of a gamma ray

Answer 12

massless

Question 13

Describe the penetration through air of alpha, beta and gamma particles

Answer 13

alpha: a few cms
bta: several metres
Gamma: long range

Question 14

What is ionisation?

Answer 14

-Ionisation is when radiation of high energy passes through matter, and can knock electrons out of atoms
-this creates free electrons and positively charged ions

Question 15

What is ionisation useful for?

Answer 15

-detecting radiation e.g GM tubes and cloud chambers

Question 16

How is ionisation pottentially damaging

Answer 16

can kill living cells causing mutations or possibly cancers

Question 17

What is a half-life

Answer 17

-> Time taken for activity of a parents smaple of neuclei to half it’s original level

Different isotopes have different half lives

Question 18

How do you measure half-lives?

Answer 18

-measure initial activity, Ao of the sample
-determine half life of this original activity
-measure how activity changes with time

number of parents neuclei half
mass of radioisotope present to reduce by half
activity of sample to reduce by half

look at worked example - save my exams

Question 19

Name 5 uses of radioactivity

Answer 19

-Smoke detectors
-monitoring thickness of material
-sterilising food/medical equipment

Question 20

Explain how smoke detectors use alpha rays

Answer 20

-alpha will ionise air within smoke detector, causing a current
-alpha emmiter is blocked when smoke enters detector
-alarm is triggered when sensor no longer detects alpha

Question 21

What is contamination?

Answer 21

The accidental transfer of a radioactive substance onto or into a material

Question 22

What is irradiation?

Answer 22

The process of exposing a material to ionising radiation, but not in contact with it

Question 23

2 isotopes of the same element

Answer 23

Same number of protons different number of electrons

Question 24

Atomic number

Answer 24

the number of protons in the neucleus of an atom

Question 25

mass number

Answer 25

the number of neucleons (protons+neutrons) in a neucleus

Question 26

Background radiation

Answer 26

ionising radiation from earth and space (rocks, food, cosmic rays)

Question 27

What is activity

Answer 27

number of decays per second (Bq)

Question 28

How does the geiger meter work?

Answer 28

The Geiger-Muller tube is a device that detects radiation. It gives an electrical signal each time radiation is detected. These signals can be converted into clicking sounds, giving a count rate. (in clicks per second or per minute)