Nuclear

Question 1

What is the composition of Alpha radiation ?

Answer 1

helium nucleus
2protons, 2neutrons

Question 2

What is the mass and charge of Alpha radiation ?

Answer 2

4 relative mass
+2 relative charge

Question 3

What is Beta radiation made of ?

Answer 3

A high velocity electron

Question 4

What is the mass and charge of Beta radiation ?

Answer 4

0 relative mass
-1 relative charge

Question 5

What is gamma radiation ?

Answer 5

A wave of electromagnetism (shortest wavelength)

Question 6

What is the charge and mass of gamma radiation ?

Answer 6

0 relative charge
0 relative mass

Question 7

What is one use of alpha radiation ?

Answer 7

Smoke alarms

Question 8

What is one use of beta radiation ?

Answer 8

testing paper thickness

Question 9

What is one use of gamma radiation ?

Answer 9

to be used as a medical tracer
(put into body and creates an image of the body for medical tests)

Question 10

What can alpha penetrate ?

Answer 10

A few centimetres of air
Stopped by paper

Question 11

What can beta penetrate ?

Answer 11

A few centimetres of air
A few millimetres of paper
Stopped by aluminium

Question 12

What can gamma penetrate ?

Answer 12

A few centimetres of air
A few millimetres of paper
A few millimetres of aliminium

Stopped by Thick lead

Question 13

What is the ascending order of strength in radiation ?

Answer 13

Alpha
Beta
Gamma

Question 14

What is the ascending order of ionisation in radiation ?

Answer 14

Gamma
Beta
Alpha

Question 15

Why is gamma least ionising ?

Answer 15

1 photon interacts with 1 electron
so each gamma photon can only ionise 1 atom and only if it actually hits an electron

Question 16

Why is alpha more ionising than beta ?

Answer 16

Alpha is slower (more time to interact)
Much bigger (bigger space to interact)
x2 charge (twice as likely to ionise)

Question 17

What are some sources of radiation ?

Answer 17

rocks
fallout from nuclear testing
radiation from chenauble

Question 18

How is background radiation accounted for in an experiment ?

Answer 18

count background radiation for ~10 minutes
deduct from final count

Question 19

What is the unit for activity ?

Answer 19

Number of decays per second
Bq
s^-1

Question 20

What is the unit for Intensity ?

Answer 20

Activity per unit area
Bq m^-2
s^-1 m^-2

Question 21

What did Rutherford do in his experiment ?

Answer 21

• Alpha particles fired at very thin gold foil
• In a vacuum
  ( Had a detector to see where the particles went )

Question 22

What were the results of Rutherford’s experiment ?

Answer 22

• Most alpha particles went straight through
• Some deflected at small angles
• Some deflected at large angles (90+)

Question 23

Why did the alpha particles going straight through align with the modern structure of the atom ?

Answer 23

• Atom is mostly empty space

Question 24

Why did the alpha particles deflecting align with the modern structure of the atom ?

Answer 24

• The positive charge is held in the nucleus (like charges repel)

Question 25

What happens to the kinetic energy when a particle gets to the point of closest approach ?

Answer 25

- All converted to Electric Potential energy

Question 26

What is the graph for electron diffraction (x : diffraction angle, y : intensity of scattered electrons)

Answer 26

- Minimum angle : max intensity - Max angle : min intensity - Middle of graph has a sharp decrease that then goes to an increase (graph is not a standard curve, has 2 turning points in the middle)

Question 27

What is the purpose of electron diffraction ?

Answer 27

To get a better measurement of a nucleus radius (alpha particles are bigger and can make nucleus recoil)

Question 28

What does N mean in a Nuclear decay equation ?

Answer 28

Number of undecayed nuclei

Question 29

What does N0 mean in a Nuclear decay equation ?

Answer 29

Number of Nuclei at the start

Question 30

When can the Activity equation ( ΔN / Δt = -A = λN) be used

Answer 30

If given a graph

Question 31

What is the unit for Count rate ?

Answer 31

Bq counts per time period

Question 32

What is a half life ?

Answer 32

- Time taken for activity to half - Time taken for number of undecayed nuclei to half

Question 33

What is the unit for decay constant (λ)

Answer 33

s^-1

Question 34

How to find the half life from a graph ?

Answer 34

From a y value, use the graph to find out how long it takes to half and repeat 3 times

Question 35

On a graph with number of neutrons against number of protons where is beta- decay ?

Answer 35

just above the line for stable nuclei

Question 36

On a graph with number of neutrons against number of protons where is beta+ decay / electron capture ?

Answer 36

Just below curve

Question 37

On a graph with number of neutrons against number of protons where is alpha decay ?

Answer 37

further below the line than beta+

Question 38

What is binding energy ?

Answer 38

Energy difference when nucleons join via strong

Question 39

How to calculate binding energy ?

Answer 39

Calculate initial mass of protons + neutrons Calculate total mass of nucleus Sub Mass difference into E = mc^2

Question 40

What is fusion ?

Answer 40

When 2 nuclei come together to make a bigger nucleus

Question 41

What are the conditions for fusion ?

Answer 41

- Travelling fast enough to overcome electrostatic repulsion - High temperature - Lots of nuclei

Question 42

What is fission ?

Answer 42

When a large nucleus splits into 2 smaller nuclei

Question 43

What is a fission chain reaction ?

Answer 43

n —> (big nucleus) —> 2 smaller nuclei + 3n

Question 44

What is a thermal neutron ?

Answer 44

A neutron with 1eV of kinetic energy

Question 45

Why does a thermal neutron need 1eV of kinetic energy to induce fission ?

Answer 45

Too much energy it will go right through the nucleus Too little energy it will bounce off

Question 46

Why does a thermal neutron need 1eV of kinetic energy to induce fission ?

Answer 46

Too much energy it will go right through the nucleus Too little energy it will bounce off

Question 47

What does a moderator do ?

Answer 47

- Slows down neutrons (so they have 1eV Ek) through inelastic collissions - Made from graphite or water (to not absorb neutrons)

Question 48

What do fuel rods do ?

Answer 48

- Contains the fuel - Makes it easier to change fuel - Used up over time so become less effective - Usual fuel is uranium

Question 49

What does a coolant do ?

Answer 49

- Removes heat from the reactor - Usually made of water or carbon dioxide

Question 50

What do the control rods do ?

Answer 50

- Absorb neutrons from the fission so that 1 is left - Can be move further in to slow down reactions - Can be moved further out to speed up - Can be made from Boron or Cadmium

Question 51

Why does the Nuclear Reactor get hot ?

Answer 51

- Neutrons collide with the moderator - Atoms gain Ek

Question 52

Why does the nuclear reactor have shielding ?

Answer 52

- To absorb neutrons - Reduce intensity of gamma rays - Made from concrete

Question 53

What happens when the control rods are dropped fully in ?

Answer 53

- Absorbs all the neutrons - Stops reactions - *Stops the reactor quickly*

Question 54

How is Nuclear Waste stored ?

Answer 54

- Removed by remote control - Stored in a cooling pond for several months - Remaining waste is stored in glass and buried underground