Topic 11 Nuclear Radiation

Question 1

Explain the conditions required to bring about and maintain nuclear fusion. (3)

Answer 1

-Very high temperature and very high density needed.
-Very high temperature to provide enough energy to overcome electrostatic forces of repulsion between nuclei.
-Very high density to give big enough collision rate to maintain reaction.

Question 2

Explain how fusion and fission both release energy as binding energy per nucleon changes. (3)

Answer 2

-Fusion involves an increase in binding energy per nucleon as number of nucleons increases.
-Fission involves an increase in binding energy per nucleon as number of nucleons decreases.
-If binding energy per nucleon increases energy is released in process.

Question 3

State what is meant by binding energy. (2)

Answer 3

-When nucleons bind together to form an atomic nucleus.
-Energy equivalent to mass deficit.

Question 4

The energy radiated by stars is released by nuclear fusion.

Explain the conditions required to bring about and maintain nuclear fusion in stars. (6)

Answer 4

-Requires a very high temperature.
-Nuclei all have positive charge leading to large repulsive force between nuclei.
-At high temperature, nuclei have high kinetic energy, sufficient to overcome electrostatic forces of repulsion.
-Nuclei must get close enough to fuse.
-Requires very high density.
-Collision rate must be high enough to sustain fusion.

Question 5

Describe how to determine the corrected count rate from the source. (2)

Answer 5

-Remove source and record background count for a specific amount of time and subtract from count from the source.
-Divide this by time to find corrected count rate.

Question 6

What is spontaneous decay? (1)

Answer 6

-Decay is unaffected by external factors.

Question 7

What is random decay? (1)

Answer 7

-Each nucleus in a substance has equal chance of decaying next.