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A-Level Physics > 8) Nuclear Physics > Flashcards

8) Nuclear Physics Flashcards

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1
Q

Properties of alpha radiation

A

Two protons, two neutrons
Weakly penetrating
Easily absorbed
Positively charged

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2
Q

What nuclei can emit alpha particles

A

Nuclei with atomic number greater than 60

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3
Q

What stops each type of radiation

A

Alpha - sheet of paper
Beta - 5mm of aluminium, 30cm air
Gamma -

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4
Q

Alpha radiation applications

A

Fire alarms - alpha particles cannot pass through smoke so sets of alarms

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5
Q

Properties of beta radiation

A

Electrons (or positrons) emitted from unstable nucleus
Moderately penetrative
Either positively or negatively charged

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6
Q

Which nuclei emit what type of beta radiation

A

Beta+ emitted by proton rich nuclei
Beta- emitted by neutron rich nuclei

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7
Q

Applications of beta particles

A

Gauging thickness of aluminium sheeting or foil
Beta+ emitter used in medical PET scans

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8
Q

Radioactivity protective measures

A

Stay at arms length
Protective clothing (goggles, gloves)
Reduce exposure time
Point sources away from you
Store in lead-lined box

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9
Q

What was Rutherford’s experiment and what happened

A

Fired alpha particles at very thin pieces of gold leaf
Particles mostly passed through the gold lead but some were deflected at large angles

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10
Q

What model did Rutherford disprove

A

Plum pudding model

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11
Q

Explain Rutherford’s results of strong deflections

A

Caused by electrostatic repulsion between positive nucleus and positive alpha particles
Most alpha particles travelled through free space

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12
Q

What model did Rutherford find

A

Current atomic model

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13
Q

When and what did Democritus suggest

A

5th century BC
Matter made of lumps called atomos
All atomos identical
Atomos smallest unit of matter

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14
Q

When and what did Dalton suggest

A

1800s
Different atoms corresponded to different elements

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15
Q

What did Thomson discover

A

Electrons could be removed from atoms
Atoms were not the smallest unit of matter
Atoms were clouds of positive charge with negative electrons suspended inside
Plum pudding model

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16
Q

From latest to earliest name the leaders in atomic discovery

A

Democritus
Dalton
Thomson
Rutherford

17
Q

How does gamma radiation affect a nucleus

A

Does not change proton or nucleon number

18
Q

Properties of gamma radiation

A

Makes nucleus more stable
Highly penetrative

19
Q

What absorbs gamma radiation

A

Several centimetres of lead
Travels indefinitely through a vacuum
Part of EM spectrum

20
Q

What law does gamma radiation follow

A

Inverse square law
intensity at distance x from the source = constant / x^2

21
Q

Applications of gamma radiation

A

Medical imaging, curing cancer by destroying tumour cells
Sterilisation
Food irradiation

22
Q

Explain experiment for inverse square law

A

1) Find background radiation (Geiger-Muller tube) (repeat for average)
2) Position source into holder, position GM tube at different distances from source, measure count rate at each distance several times and find average
3) Calculate corrected count rate per minute = average count rate at each distance - average background count
4) Plot graph of count rate against 1 / x^2 where x is distance between source and GM tube. Straight line through origin proves inverse square law

23
Q

Sources of background radiation

A

Radon gas (from the ground)
Buildings (brick)
Cosmic rays (sun and space)
Medical procedures
Food and drink

24
Q

What experimental error is there in radiation experiments

A

Not deducting background radiation

25
Q

How do we measure decay and why

A

Decay is random and spontaneous so we look at the count rate over a long time to see if it decreases

26
Q

What is the probability that a nucleus will decay in a given time proportional to

A

The number of nuclei

27
Q

Equation for calculating rate of decay

A

Rate of nuclei decay = decay constant x number of nuclei
λ is the decay constant
N is the number of nuclei

28
Q

NOT DONE 2ND SLIDESHOW OF 8.1.4

A

X

29
Q

What is a half life

A

Time taken for number of radioactive nuclei (activity) in a sample to halve

30
Q

What is the activity of a sample directly proportional to

A

The number of nuclei remaining

31
Q

Equation for decay activity

A

Activity = decay constant x number of nuclei remaining

32
Q

Benefits of nuclear power

A

No CO2 released
Responds well to demand changes
Output per unit mass of fuel is far higher than hydrocarbon sources such as oil, coal or gas

33
Q

Negative of nuclear power

A

Some waste materials need storage for hundreds or thousands of years in a secure geographically stable location in steel containers

34
Q

What can be done with low level radioactive waste

A

A-Level Physics (4 decks)

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