A very small sphere of mass `80 g` having a charge q is held at a height of `9 m` vertically above the center of a fixed conducting sphere of radius `1 m`, carrying an equal charge q. When released, it falls until it is repelled back just before it comes in contact with the shpere as shown in Fig. 47. Calculate the charge `q. [g = 10 ms^-2]`.

Explanation

To solve the problem, we will use the principle of conservation of energy, considering both gravitational potential energy and electric potential energy.

### Step-by-Step Solution

1. **Identify Given Values**:
- Mass of the small sphere, \( m = 80 \, \text{g} = 0.08 \, \text{kg} \)
- Height above the center of the conducting sphere, \( h = 9 \, \text{m} \)
- Radius of the conducting sphere, \( R = 1 \, \text{m} \)
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