Nuclear fusion reactions inside stars and reactors produce energy. One proposed reaction involves two protons (11H{}^1_1\text{H}11H) and two neutrons (01n{}^1_0\text{n}01n) fusing to form a helium-4 nucleus (24He{}^4_2\text{He}24He):
2 11H+2 01n→24He 2 \ {}^1_1\text{H} + 2 \ {}^1_0\text{n} \rightarrow {}^4_2\text{He} 2 11H+2 01n→24HeIn this reaction, 28.3 MeV28.3\text{ MeV}28.3 MeV of energy is released.
Only one of the particles in the reaction has a non-zero binding energy. Determine the binding energy per nucleon of this particle. Explain your answer.
Explain why initiating a fusion reaction between two positive nuclei requires extremely high temperatures.
A high-energy gamma photon can spontaneously create a proton-antiproton pair (pair production). Calculate the maximum wavelength of a gamma photon for this pair production event.
(Mass of a proton, mp=1.67×10−27 kgm_{p} = 1.67 \times 10^{-27}\text{ kg}mp=1.67×10−27 kg; Planck constant, h=6.63×10−34 J sh = 6.63 \times 10^{-34}\text{ J s}h=6.63×10−34 J s; speed of light, c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1)
90 exam-style questions on OCR A A Level Physics Nuclear and particle physics, covering The nuclear atom, Fundamental particles, Radioactivity, and Nuclear fission and fusion. Each one has a worked solution and a mark scheme showing where the marks go.