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IGCSE Physics > Chapter 5: Nuclear Physics > Flashcards

Chapter 5: Nuclear Physics Flashcards

1
Q

What is the atom made up of?

A

A small dense positively charged nuclei containing protons and neutrons, surrounded by negatively charged electrons.

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2
Q

What is nuclear fission?

A

A nuclear reaction or a radioactive decay process where the nucleus of an atom splits into smaller parts.

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3
Q

What does nuclear fission produce?

A

Free neutrons, gamma photons and a very large amount of energy.

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4
Q

What is nuclear fusion?

A

A reaction where two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles.

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5
Q

Why are large amounts of energy produced during nuclear fusion?

A

Because of the difference in mass between the reactants and products.

This arises due to the difference in atomic ‘binding energy’ between the atomic nuclei before and after the reaction.

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6
Q

What are the three isotopes of hydrogen?

A

Protium
Deuterium
Tritium

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7
Q

What is background radiation?

A

Ionising radiation present in the environment at a particular location which is not due to the radiation of radiation sources.

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8
Q

What can background radiation be caused by?

A

Both:
natural sources
artificial sources

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9
Q

What does background radiation include?

A

Cosmic radiation
Environmental radioactivity from naturally occurring radioactive materials like radon and radium

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10
Q

Can radiation be detected by human senses?

A

No

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11
Q

How is radiation detected using a GM counter?

A
  1. Radiation enters through a thin-end window made or mica or through the wall (if the radiation is very penetrating).
  2. These are accelerated towards the electrodes and cause more ionisation by colliding with other argon atoms.
  3. Upon reaching the electrodes, the ions produce a current pulse which is amplified and fed to a scalar or a ratemeter.
  4. A scalar counts the pulses and shows the total received in a certain time
  5. A ratemeter gives the counts per second/minuted directly. It usually has a loudspeaker which gives a ‘click’ for each pulse.
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12
Q

How is Activity (radioactivity) measured?

A

Becquerels (Bq)

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13
Q

What is Activity?

A

The number of radioactive atoms which disintegrate and emit radioactivity per second.

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14
Q

Tell me the formula for Activity.

A
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15
Q
A
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16
Q

How do you find out the background radiation levels?

A
  1. With no radioactive sources in the room, start a stopwatch and GM tube at the same time
  2. AFter 60s stop the GM tube and counter and record the number of counts in 60 s
  3. Calculate background activity in the room
  4. Repeat the process a number of times and find the average background activity.
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17
Q

Why are some atomic nuclei unstable?

A

Because of an imbalance in the forces within the nucleus.

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18
Q

What is radioactive decay?

A

The process of emitting radiation.
The spontaneous transformation of an unstable nucleus into a more stable one by the release of radiation.
It is a random process.

19
Q

What are the three types of radiation?

A

Alpha
Beta
Gamma

20
Q

What do alpha particles consist of?

A

two protons and two neutrons identical to a helium nucleus.

21
Q

What is the relative charge of an alpha particle?

A

+2

22
Q

Tell me the properties of alpha particles.

A
  1. They have a higher mass compared with beta particles
  2. Can be deflected by magnetic or electric fields
  3. They leave a dense trail of ions behind them, affecting virtually every atom they meet.
  4. They have a short range, making them relatively harmless if handled carefully, but they have the potential to be extremely dangerous if the alpha emitter enters the body.
23
Q

Tell me the speed of alpha particles.

A

3.0 x 10^7

24
Q

What is a beta particle?

A

A high energy, high speed electron

25
Q

What is the relative charge of beta particles?

A

-1

26
Q

Tell me the properties of beta particles.

A
  1. Beta particles have a lower mass compared with alpha particles.
  2. Beta particles can be deflected by magnetic or electric fields
  3. They create a less dense trail of ions than alpha and consequently have a longer range
  4. Tend to be more dangerous than alpha particles because they are able to travel further and penetrate the skin and yet are still ionising enough to cause significant damage.
27
Q

Tell me the speed of beta particles.

A

2.7 x 10^8 m/s

28
Q

What is gamma radiation?

A

It is part of the electromagnetic spectrum.
It has no charge or mass
They are not deflected by magnetic or electric fields
They are more penetrating and have a greater range
Makes them hazardous in large amounts
They travel at the speed of light.

29
Q

Tell me what is alpha decay.

A

When an alpha particle is emitted from a nucleus, the nucleus loses two protons and two neutrons

This means the atomic mass number decreases by 4 and the atomic number decreases by 2.

30
Q

Write the eqn for the alpha decay of Uranium.

A
31
Q

Write the eqn for the alpha decay of Radium.

A
32
Q

What happens during beta decay?

A

A neutron changes into a proton plus an electron.

33
Q

Write the eqn for the beta decay of carbon-14.

A
34
Q

Write the eqn for the beta decay of carbon-10.

A
35
Q

Is there a change in mass for gamma decay?

A

No because it is a type of electromagnetic radiation

36
Q
A
37
Q
A
38
Q

How are alpha particles used in smoke detectors?

A

If smoke enters the detector, some of the alpha particles are absorbed and the current drops, triggering the alarm.

39
Q

How are beta particles used as thickness monitors?

A

A source and receiver are placed on either side of the sheet during its production.
If there is a drop or rise in the number of beta particles detected, then the thickness of the sheet has changed and needs to be adjusted.

40
Q

What are gamma emitters used for?

A

Sterilisation of equipment
Short half-life gamma emitters cam be used as tracers in medicine
Irradiating food

41
Q

What is the effect of ionising radiation in living cells?

A

The radiation enters collides with molecules and cause ionisation, damaging or destroying the molecules.
Higher dosages of radiation can kill cells completely, causing radiation sickness
Lower dosages cause cells to become cancerous, when they divide uncontrollably

42
Q

What does the harmful effects of radiation depend on?

A
  1. Amount of exposure there is to the radiation
  2. The energy and penetration of the radiation emitted.
43
Q

What are the safety precautions when handling radioactive material?

A
  1. Use tongs to pick up sources
  2. Keep radioactive material in lead-lined containers
  3. Keep radiation sources as far away from the body as possible
  4. Wear protective clothing
  5. Prevent inhalation of radioactive dust particles and avoid direct skin contact
  6. Limiting exposure time to radioactive sources
  7. Immediately return radiation source to lead-lined box when not required
  8. Use remote controlled robot arms in highly radioactive areas when handling radiation materials.
44
Q
A

IGCSE Physics (21 decks)

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