Distance of closest approach d (head-on α-particle)निकटतम उपगमन दूरी d (आमने-सामने आता α-कण)Distance of closest approach d (head-on α-particle)

NCERT Example 12.2 · Class 12 Physics · Chapter 12 · interactive diagram

Parts and what they mean

• Incoming α-particle (आता हुआ α-कण) — Far from the nucleus all its energy is kinetic, K.
• α-particle momentarily at rest (क्षण भर विराम में α-कण) — All the kinetic energy has become electric potential energy U = (1/4πε₀)(2e)(Ze)/d. Then it is pushed back.
• Gold nucleus (+79e) (स्वर्ण नाभिक (+79e)) — Treated as fixed, being about 50 times heavier.
• Distance of closest approach d (निकटतम उपगमन दूरी d) — Centre-to-centre distance at the turning point. Because the α-particle never touches the nucleus, d gives an upper limit for the nuclear radius.

Original diagram drawn by Simple Learning Hub, based on NCERT Example 12.2. Report a mistake