Question: What is the voltage across a capacitor after one time constant in an RC charging circuit?

Options:

1. 63.2% of the supply voltage
2. 50% of the supply voltage
3. 100% of the supply voltage
4. 36.8% of the supply voltage

Correct Answer: 63.2% of the supply voltage

Solution:

After one time constant, the voltage across the capacitor reaches approximately 63.2% of the supply voltage.