A-Level Physics: Nuclear Energy

Nuclear energy is where A-Level Physics connects its deepest equation — E = mc² — to working technology, and exam questions move freely between the binding-energy curve and the engineering of a reactor. This quiz covers that whole span.

The mass-energy questions apply Einstein's relation in the direction students find harder: recovering the mass change from a released energy (a calculation whose answer key was independently recomputed and corrected during verification — 1.67 × 10⁻²⁸ kg, a full power of ten from the value originally keyed). Binding energy per nucleon is computed directly for a given nucleus, and the definitions question — expanded during verification — establishes that binding energy is equally the energy to disassemble a nucleus and the energy released on its formation, both equal to the mass defect times c².

The curve questions do the conceptual heavy lifting: the peak at iron-56, why fusion of light nuclei climbs the curve and releases energy, and the two-part explanation — greater stability, lost mass — of why hydrogen-to-helium fusion powers stars.

The reactor questions cover the full engineering set: what maintains a controlled chain reaction (moderator to thermalise neutrons, control rods to absorb them), what happens when the moderator is removed (fission probability collapses for fast neutrons), which features genuinely constitute reactor safety, and a power-station efficiency calculation converting electrical output back through 30% efficiency to thermal energy per hour.

All constants and values are supplied, consistent with the data-booklet exam, and the explanations keep the curve — rather than memorised slogans — at the centre of every energy argument.

• Apply E = mc² in both directions with correct powers of ten
• Define binding energy both ways and relate it to the mass defect
• Use the binding energy per nucleon curve to explain fission and fusion energetics
• Explain the roles of moderator and control rods in a controlled chain reaction
• Work reactor power and efficiency calculations

Topic scope follows section 3.8 (Nuclear physics) of the current A-level physics subject content: mass-energy equivalence, binding energy and the binding energy per nucleon curve, induced fission, chain reactions and nuclear reactor safety.