The proton–proton (p, p) cycle in the Sunसूर्य में प्रोटॉन–प्रोटॉन (p, p) चक्रThe proton–proton (p, p) cycle in the Sun

NCERT Eq. 13.14–13.15 · Class 12 Physics · Chapter 13 · interactive diagram

Parts and what they mean

• (i) ¹H + ¹H → ²H + e⁺ + ν + 0.42 MeV ((i) ¹H + ¹H → ²H + e⁺ + ν + 0.42 MeV) — Two protons form a deuteron; one proton changes into a neutron, giving out a positron and a neutrino.
• (ii) e⁺ + e⁻ → γ + γ + 1.02 MeV ((ii) e⁺ + e⁻ → γ + γ + 1.02 MeV) — The positron meets an electron; they annihilate into two gamma photons (2 × 0.511 MeV).
• (iii) ²H + ¹H → ³He + γ + 5.49 MeV ((iii) ²H + ¹H → ³He + γ + 5.49 MeV) — The deuteron captures a proton to make light helium, ³He.
• (iv) ³He + ³He → ⁴He + ¹H + ¹H + 12.86 MeV ((iv) ³He + ³He → ⁴He + ¹H + ¹H + 12.86 MeV) — Two ³He nuclei (so (i)–(iii) happen twice) make ordinary helium and give back two protons.
• Net result (कुल परिणाम) — 2(i) + 2(ii) + 2(iii) + (iv): 2(0.42) + 2(1.02) + 2(5.49) + 12.86 = 26.72 ≈ 26.7 MeV. Four hydrogen atoms → one helium atom.

Original diagram drawn by Simple Learning Hub, based on NCERT Eq. 13.14–13.15. Report a mistake