Nuclear

Question 1

charge on proton/electron (not exact coulombs)

Answer 1

1e

Question 2

alpha decay equation and process

Answer 2

helium nucleus (2p, 2n)
mass number down by 4, atomic number down by 2

Question 3

beta decay equation and process

Answer 3

• a electron or positron given off
• neutron turns into proton or vice versa
• mass number same, atomic number one up or one down
• anti neutrino for -, neutrino for +

Question 4

Ionisation
Penetration
Stopped By

Answer 4

Alpha, Beta, Gamma

Ionisation: high, mid, low
Penetration: low, mid, high
Stopped By: paper, aluminium, lead

Question 5

uses of three radiations

Answer 5

alpha: smoke detector
beta: paper thickness gauge
gamma: sterilising, radiotherapy

Question 6

What is gamma radiation

Answer 6

nucleus does not change
gets rid of spare energy

Question 7

Decay constant in radioactivity

Answer 7

λ
probability of a nucleus decaying in the next second

Question 8

Bq

Answer 8

number of decays per second

Question 9

Half life meaning

Answer 9

time taken for radioactive activity to half

Question 10

Activity, decay constant, number of undecayed nuclei left

Answer 10

A = λN

Question 11

ratio of activity, mass, number against time and decay constant

Answer 11

A/A0 = M/M0 = N/N0 = e^-λt

Question 12

half life equation

Answer 12

t = ln(2)/λ

where t is half life

Question 13

time constant meaning (2)

Answer 13

time when we have 37% of original value
(1/e)

when λt = 1

Question 14

time constant, decay constant

Answer 14

tc = 1/λ

where tc is time constant

Question 15

measured activity / true activity

when a small detector is measuring count from a central gamma source

Answer 15

measured activity / true activity

Area of detector/4πr^2

Question 16

intensity from radiation source

Answer 16

intensity = radiation/area

I = k/4πr^2

Question 17

intensity, distance realstionship

Answer 17

I ∝ 1/r^2

I1r1^2 = I2r2^2

• if detector moved x3 far away, intensity down by 1/9

Question 18

parts of a fission reactor and purposes

Answer 18

• coolant - remove heat from core
• fuel rods
• moderator - slows down neutrons to increase fission (eg. water)
• control rods - absorbs some neutrons to reduce chain reaction (eg. boron)

Question 19

what they do with radioactive waste

Answer 19

vitrify and bury

Question 20

where Fusion happens

Answer 20

sun
H- bombs

Question 21

unit of relative atomic mass

Answer 21

1u

Question 22

mass of constituents vs mass of nucleus

Answer 22

mass of constituents > mass of nucleus

Question 23

mass defect

Answer 23

change in mass from nucleus constituents to nucleus
converted to energy

Question 24

binding energy

Answer 24

energy required to separate a nucleus/atom into its constituents

Question 25

energy, mass

Answer 25

E = Δmc^2

where mass is in kg

Question 26

1u to kg

Answer 26

1u = 1.67 x 10^-27 kg

Question 27

u to MeV

Answer 27

x 931.3

Question 28

1 MeV to joules

Answer 28

1 MeV = 1.6 x 10^-13 J

Question 29

binding energy change in fission and fusion

Answer 29

• total binding energy increased
• mass lost

Question 30

what makes nucleus stable (binding energy)

Answer 30

binding energy per nucleon increases

Question 31

cone of stability and where types of radiation happen

Answer 31

• stability cone above N = Z
• B- above
• B+ below
• alpha top corner

Question 32

Rutherford scattering setup

Answer 32

• alpha transmitter
• gold foil
• detector that can co all the way round

Question 33

Rutherford scattering results and conclusions

Answer 33

Results
- most alpha particles passed straight through foil
- few deflected by >4
- very few deflected by >90

Conclusions
- atom is mostly empty space
- concentration of positive charge in atom
- nucleus has high density and mass

Question 34

electrical potential energy equation

Answer 34

Ep = Qq/4πε0r

where Q and q are the two charges
r is distance of separation

Question 35

find closest approach to approximate radius of nucleus

Answer 35

initially Ek = 1/2 mv^2

at point of repulsion, all Ek into Ep

Ep = (2e)(Ze)/4πε0r
1/2 mv^2 = (2Ze^2)/4πε0r

r = (Ze^2)/πε0mv^2