Question

For a practical voltage source, which of the following is correct?

(a) Cannot be less than source voltage

(b) Cannot be higher than source voltage

(c) Is always less than source voltage

(d) Is always equal to source voltage

I have been asked this question in an internship interview.

This is a very interesting question from Advanced Problems on Network Theorems topic in portion Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Correct answer is (b) Cannot be higher than source voltage

The explanation is: A practical voltage source has some resistance. Because of this resistance, some amount of voltage drop occurs across this resistance. Hence, the terminal voltage cannot be higher than source voltage. However, if current is zero, then terminal voltage and source voltage are equal.