Question

Find the equivalent resistance of the network shown in figure between the points A and B.

Answer 1

Let the potentials at A and B be V_A and V_B, respectively.

(i) When V_A > V_B, that is, a battery is connected between points A and B, with its positive terminal connected to point A and its negative terminal connected to point B:
As the potential on the p-side of the diode is greater than the potential on the n-side of the diode, the diode is forward biased; thus, it can be replaced by a short circuit.
As the two resistances are connected in parallel, the effective resistance becomes
Equivalent resistance$=\frac{10}{2}=5\mathrm{\Omega }$

(ii) When V_A < V_B:
The diode is reverse biased, so it is replaced by an open circuit. Thus, no current flows through this branch.
∴ Equivalent resistance = 10 Ω