STANDARDPhysics-Atoms

STANDARD Physics Geiger-Marsden Experiment MCQ Question

Type: MCQ-conceptual-Medium-Class 12

In a Geiger-Marsden experiment. Find the distance of closest approach to the nucleus of a 7.7 MeV α-particle before it comes momentarily to rest and reverses its direction. (Z for gold nucleus = 79)

A

10 fm

B

20 fm

C

30 fm

D

40 fm

Correct Answer

Option C

Detailed Explanation

The distance of closest approach is calculated using the conservation of energy. The initial kinetic energy of the α-particle is equal to the final electric potential energy. Using the formula d = (1/4πε₀) * (2Ze²/K), where K is the kinetic energy and Z is the atomic number, we find d = 30 fm.

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