NEET Solved Paper 2016 Question 23

Question: When an $ \alpha - $ particle of mass ’m’ moving with velocity ‘v’ bombards on a heavy nucleus of charge ‘Ze’, its distance of closest approach from the nucleus depends on m as :

Options:

A) $ \frac{1}{m} $

B) $ \frac{1}{\sqrt{m}} $

C) $ \frac{1}{m^{2}} $

D) m

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Answer:

Correct Answer: A

Solution:

  • At closest distance of approach, the kinetic energy of the particle will convert completely into electrostatic potential energy.
    $ \Rightarrow $ $ \frac{1}{2}mv^{2}=\frac{KQq}{d}\Rightarrow d\propto \frac{1}{m} $