Two point charges `20xx10^(-6)C and -4xx10^(-6)C` are separated by a distance of 50cm in air, Find (i) the point on line joining the charges, where the electrostatic potential is zero (ii) Also, Calculate the electrostatic potential energy of the system.

Explanation

### Step-by-Step Solution:

#### Part (i): Finding the Point Where Electrostatic Potential is Zero

1. **Identify the Charges and Distances:**
- Charge \( q_1 = 20 \times 10^{-6} \, \text{C} \)
- Charge \( q_2 = -4 \times 10^{-6} \, \text{C} \)
- Distance between charges \( d = 50 \, \text{cm} = 0.5 \, \text{m} \)
...