Nuclear Physics

Question 1

What is an alpha particle?

Answer 1

2 protons and 2 neutrons

Question 2

What is a beta particle?

Answer 2

High energy electron ejected from the nucleus

Question 3

What is a gamma particle?

Answer 3

High energy electromagnetic radiation wave

Question 4

What is nuclear fission?
Describe its process

Answer 4

• nucleus splits
• nucleus absorbs neutron
• nucleus splits into 2 smaller nuclei, 2/3 neutrons, gamma radiation and kinetic energy
• neutrons admitted absorbed by more nuclei triggering fission again (chain reaction)

Question 5

Where does nuclear fission take place?

Answer 5

• energy released in a reactor (controlled)
• gamma rays and kinetic energy of fission absorbed by water, heating it
• steam produced generates electricity

-explosion in nuclear weapon caused by uncontrolled fission chain reaction

Question 6

What are uses of radiation in medicine?

Answer 6

• radioactive tracers explore internal organs
• short half life so not in body for long
• gamma rays pass through body and are detected

Question 7

What are uses of radiation in radiotherapy?

Answer 7

• gamma rays treat cancer
• carefully focused to kill cancer cells
• minimise damage to healthy tissues/cells

Question 8

What is nuclear fusion?
What happens?

Answer 8

• 2 low mass nuclei join together to form a heavier nucleus
• some of the mass of the nuclei can be converted to energy which is released as radiation
• E = mc squared

Question 9

What is background radiation?

Answer 9

Radiation present all around in the environment

Question 10

What are natural sources of background radiation?

Answer 10

• radioactive rock
• cosmic rays from space

Question 11

What are man made sources of background radiation?

Answer 11

• nuclear accidents
• fall out from weapons testing

Question 12

What is carbon dating?

Answer 12

• half life or 5600 years
• measures age of ancient wood: other organic material
• measure count rate of radioactive carbon by compare to count rate of wood

Question 13

What is uranium dating?

Answer 13

• half life of 4500 million years
• measure age of igneous rock
• decays to form atom of lead
• work out age of rock, compare to lead atoms

Question 14

Give the 2 definitions of half life

Answer 14

1) time it takes for number of radioactive nuclei in a sample to halve
2) time taken for number of decays or activity to halve its initial level

Question 15

What is irradiation

Answer 15

• exposing an object to nuclear radiation
  -object does not become radioactive
• only comes in contact with irradiation not isotope itself

Question 16

What model of the atom did the alpha scattering experiment lead to by Neil Bohr and what did it state?

Answer 16

• nuclear model
• negative electrons orbit positive nucleus at fixed distances/shells

Question 17

What was the alpha scattering experiment?
Why was gold used?

Answer 17

• alpha particles fired at a piece of thin gold foil
• gold can be hammered into a few atoms thick

Question 18

What is the ionising power of?
1) alpha
2) beta
3) gamma

Answer 18

1) very strongly ionising
2) quite strongly ionising
3) weakly ionising

Question 19

What is ionising radiation?
What are its risks?

Answer 19

-radiation that has enough energy to knock electrons off atoms so atoms become charged
-damage living tissue, mutate cells, cell death, increase likelihood of cancer