Radiation

Question 1

What are ions?

Answer 1

Charged particles from atoms gaining/losing electrons.

Ionising radiation (alpha, beta, gamma) forces an electron away from an atom creating a charged ion.

Question 2

Radiation timing?

Answer 2

Radiation is spontaneous. It can either happen in a few seconds or multiple years or even more/less.

Question 3

What is nuclear radiation?

Answer 3

• If a nucleus is unstable it emits radiation to become stable.
• The nucleus changes into a new element.

Question 4

What is radioactive decay?

Answer 4

When nuclei randomly emits alpha, beta or gamma particles.

Question 5

What is an alpha particle?

Answer 5

Contains two protons and two neutrons.

(Same as Helium nucleus)

Symbol = α

Question 6

What is a beta particle?

Answer 6

A fast-moving electron, emitted from the nucleus of a decaying atom.

A neutron in the nucleus becomes positive as a result.
Symbol = β

Question 7

What is gamma radiation?

Answer 7

A high energy, short wavelength electromagnetic wave.

Emitted from the nucleus after alpha or beta decay.

Possesses no mass or charge.
Element stays the same.
Symbol = γ

Question 8

What are safety protocols for radiation?

Answer 8

• Minimise exposure time
• Maximise distance
• Maximise barriers between source (shielding)
• A person’s exposure to radiation must be measured to ensure their safety

Question 9

Type of radiation, the range, the ionising power and the material that prevents penetration?

Answer 9

1. Alpha, 5cm, high, paper
2. Beta, 15cm, medium, thin aluminium
3. Gamma, unlimited, weak, thick lead

Question 10

Range of radiation?

Answer 10

1. Alpha is likely to collide with particles (like air within first 5cm)
2. Beta can squeeze through gaps
3. Gamma is undisrupted as a wave

Question 11

What is activity?

Answer 11

The number of nuclear decays per second.

Measured in becquerels (Bq)

Question 12

What is the formula for activity?

Answer 12

A=N/t

Activity (Bq) = Number of nuclear decays / time (seconds)

Question 13

What is count rate?

Answer 13

The number of decays measured by a Geiger-Muller tube per second (less than activity)

Question 14

What does background radiation come from?

Answer 14

Mostly natural: Cosmic rays, animals, rocks (radon gas), soil and plants.
Artificial sources: x-rays, nuclear missiles and nuclear power.

Question 15

What can ionising radiation do?

Answer 15

• Damage DNA and genes
• Change the function of cells or kill them
• Can develop cancer cells

Question 16

What is absorbed dose?

Answer 16

The energy (Joules) absorbed by radation by 1kg of tissue. Measured in Grays (Gy)

Question 17

What is the equation for absorbed dose?

Answer 17

D=E/m

D = Absorbed Dose (Gy), E = Energy (J), m = mass (kg)

Question 18

What is radiation weighting factor?

Answer 18

Different types of radiation cause varying damage, so they are given weighting factors (Wr)

Question 19

What is equivalent dose?

Answer 19

Measures the biological harm done by radiation (Seiverts (H))

Question 20

What is the equation for equivalent dose?

Answer 20

H=DWr

H = Equivalent dose (Sv) D = Absorbed dose (Gy) Wr = Weighting factor

Question 21

What is equivalent dose rate?

Answer 21

• Equivalent doses can only be compared fairly if they have been inflicted in the same period of time.
• Equivalent dose rate is found by dividing equivalent dose by time.

Question 22

What is the equation for equivalent dose rate?

Answer 22

Ḣ = H/t

Ḣ = Equivalent dose rate (Sv)
H = Equivalent dose (Sv)
t = time (seconds/hours/years)

Question 23

Properties of radiation?

Answer 23

Mass

• Alpha = Heavier than beta
• Beta = Lighter than alpha
• Gamma = No mass

Charge

• Alpha = Positively Charged
• Beta = Negatively Charged
• Gamma = No charge

Deflection in Electric Field

• Alpha = Attracted to negative plate, repelled from postive plate
• Beta = Attracted to positive plate, repelled from negative plate
• Gamma = No deflection

Question 24

What are applications of nuclear radiation?

Answer 24

1. Electricity Generation
   * Nuclear Fission Power Station
   * Nuclear Fusion to create energy
2. Cancer Treatment
   * Radiotherapy cancer treatment (gamma)
3. Medical Uses
   * Sterilisation e.g. gamma rays kill bacteria
   * Tracers e.g. x-rays
4. Industrial Uses
   * Smoke detectors (smoke stops alpha particles)
   * Measuring thickness of paper
   * Tracers to map movement and/or leaks

Question 25

What is half-life?

Answer 25

The time taken for the activity of a radioactive source to half.

Question 26

How could you determing the half life of a source on a graph?

Answer 26

Question 27

How can half-life be measured?

Answer 27

**Equipment** 1. Radioacitve source 2. Geiger-Müller tube 3. Counter 4. Stopclock **Method** 1. Measure the count in a set interval 2. Repeat at regular intervals 3. Measure the background (count) and subtract

Question 28

What is nuclear fission?

Answer 28

**When a large nucleas of an atom splits into two or more nuclei.**

Question 29

What are the steps of nuclear fission chain reaction?

Answer 29

1. A neutron bombards a urnaium nucleus. 2. A neutron is absobed making the nucleus unstable 3. The unstable nucleus splits into two smaller nuclei 4. Neutrons are also released. Those neutrons bombard more nuclei. 5. Process repeats. 6. Heat given off.

Question 30

What are the two types of fission?

Answer 30

**Nuclear Reactors** 1. If the number of neutrons released is controlled then the reaction has a steady rate. **Nuclear Bomb** 2. If the number of neutrons is left to increase, the fission reaction increases in rate until it explode.

Question 31

What is nuclear fusion?

Answer 31

The reaction of two nuclei of smaller mass number combining to produce a nucleus of larger mass number.

Question 32

What are characteristics of nucleur fusion?

Answer 32

**Can take place at extremely high temperatures.** **Fusion reactions are important because they can release energy.** * Plasma Containment is required to sustain nuclear fusion reactions in a reactor. * Plasma requires strong magnetic fields to hold it in place.

Question 33

Radiation prefix rules?

Answer 33

The appropriate number of significant figures must be used in the final answer. * The final answer can have no more significant figures than the value with the least number of significant figures used in the calculation.