Choose the correct circuit which can achieve the bridge balance.

Question

Professor PC Thomas Classes · Answer

(a) : For the bridge to be balanced, the arm containing diode should have $15 \Omega$ resistance and diode in forward bias. In option (b) and (d), diode is in reverse bias and in option (c) diode is in parallel with a $5 \Omega$ resistance, so effective resistance of this arm is less than $5 \Omega$. So the correct option is (a) as diode is in series with $5 \Omega$ resistance which can give an equivalent resistance of $15 \Omega$ in case if the diode is considered not ideal.