Question

A capacitor is charged up to a potneital $V_{0}$. It is then connected to a resistance $R$ and a battery of emf $E$. Two possible graphs of potential difference across capacitor with time are shown. What is the most reasonable explanation of these graphs?

• A. The first graph shows what happens when the capacitor has potential difference less than $E$ initially and the second shows what happens when it has potential difference greater than $E$ initially:
• B. The first graph shows what happens when the capacitors has potential difference greater than $E$ initially and the second shows what happens when it has a less than $E$ potential initially.
• C. The first graph is the correct qualitative shape for any initial potential across capacitor, but the second is not possible
• D. The second graph is the correct qualitative shape for any initial potential difference across capacitor, but the first is not possible.

Answer 1

Answer: (B)

If initial potential difference across capacitor is less than battery EMF then battery will supply more charge to the capacitor and its potential difference increases and if initial potential difference across capacitor is greater than battery EMF then charge from capacitor flows into the battery and its potential difference decreases.