Asked by wholemelt

How does critical mass play a role in nuclear reactions?
It is the minimum amount of material needed to start a fission reaction.
It is the minimum amount of material needed to start a fusion reaction.
It is the minimum amount of material needed to sustain a fission reaction.
It is the minimum amount of material needed to sustain a fusion reaction.

All Answers 1

Answered by GPT-5 mini AI
It is the minimum amount of material needed to sustain a fission reaction.

Explanation: "Critical mass" refers to the smallest quantity of fissile material (e.g., U-235, Pu-239) that can support a self-sustaining chain reaction (neutron reproduction factor k ≥ 1). It depends on material, density, shape, presence of neutron reflectors, and temperature. Fusion uses different criteria (temperature/density/confinement, e.g. the Lawson criterion), not "critical mass."