When a current drawn from a battery is 0.5 A, its terminal potential difference is 20 V. And when current drawn from it is 0.2 A, the terminal voltage reduces to 16 V. Find out, emf and internal resistance of the battery.

Explanation

To solve the problem, we will use the relationship between the electromotive force (emf), terminal voltage, current, and internal resistance of the battery. We have two scenarios to work with.

### Given:
1. When current \( I_1 = 0.5 \, A \), terminal voltage \( V_1 = 20 \, V \).
2. When current \( I_2 = 0.2 \, A \), terminal voltage \( V_2 = 16 \, V \).

### Step 1: Write the equations for both scenarios

...