Nuclear fusion
3 marks · EasyThe diagram shows the reaction between a deuterium nucleus and a tritium nucleus.
Explain why a very high temperature is needed for fusion to occur between deuterium and tritium nuclei.
State one reason why fusion reactions are difficult to achieve on Earth, besides temperature.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Very high temperatures are needed so that nuclei move fast enough to overcome the electrostatic repulsion between their positive charges and collide for fusion to occur.
(b) Fusion requires very high pressures to keep nuclei close together; achieving these high pressures on Earth is difficult.
Also accept: Strong magnetic containment also accepted for b
Common mistakes: Not mentioning repulsion or pressure
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Mentions that nuclei must overcome electrostatic/repulsive forces.
M2 (a) · 1 mark · States high temperature provides kinetic energy for nuclei to move fast and collide.
B1 (b) · 1 mark · States high pressure is needed or containment is difficult.
Worked solution
a) High temperature means nuclei move faster and have enough energy to overcome the repulsive electrostatic forces between the positive charges. This allows them to get close enough to fuse.
b) Fusion also requires very high pressures to keep the nuclei close together, which is hard to produce and maintain on Earth.