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 2.0 A, the terminal voltage reduces to 16 V. Find out. `e.m.f` and internal resistance of the bettery.

Explanation

To solve the problem, we need to find the electromotive force (e.m.f) and the internal resistance of the battery using the given data. We will use the formula for terminal voltage, which is given by:

\[ V = E - I \cdot r \]

where:
- \( V \) is the terminal voltage,
- \( E \) is the e.m.f of the battery,
- \( I \) is the current flowing through the circuit,
...