Nuclear Fusion & Chapter Summary Challenge
25 NEET-standard questions on nuclear fusion, the Coulomb barrier, thermonuclear fusion in the Sun and the proton–proton cycle, controlled fusion and plasma, fusion versus fission per nucleon, and the chapter summary: binding energy, Q value, nuclear size and density. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 13 · pp. 315–320Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Why fusion releases energyLight nuclei fuse into a nucleus higher on the binding energy curve.More B.E. per nucleon = energy released
Coulomb barrier≈ 400 keV for two protonsHigher for larger charges
Temperature estimate(3/2)kT = K, T = 2K / 3k400 keV → about 3×10⁹ K
Thermonuclear fusionFusion by raising the temperature so nuclei beat the barrier.Sun’s core 1.5×10⁷ K: fast protons do it
The p–p cycle4 ¹H → ⁴He + 2ν + 6γ + 26.7 MeVSteps (i)–(iii) run twice per step (iv)
Per nucleonfusion ≈ 6.7 MeV, fission ≈ 0.8 MeVCompare per nucleon, not per event
Controlled fusion≈ 10⁸ K → plasma → confine itNo container can stand it
Chapter summaryR = R₀A^(1/3), Q = (mi − mf)c²B.E. per nucleon ≈ 8 MeV for A = 30 to 170
right first tryfixed after explanationstill to fix
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