In a Geiger - Marsden experiment, calculate the distance of closest approach to the nucleus of Z=75, when an `alpha` - particle of 5 Me V enery impinges on it before it comes momentarily to rest and reverses its direction.
How will the distance of closest approach be affected when the kinetic energy of the `alpha`-particle is doubled ?

Explanation

To solve the problem of calculating the distance of closest approach to the nucleus in a Geiger-Marsden experiment, we will follow these steps:

### Step 1: Write down the given data
- Atomic number of the nucleus (Z) = 75
- Kinetic energy of the alpha particle (KE) = 5 MeV

### Step 2: Convert the kinetic energy from MeV to Joules
1 MeV = \(1.6 \times 10^{-13}\) Joules. Therefore,
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