Find the equivalent resistance of the network shown in figure between the points A and B.
Case 1: Potential at terminal A > Potential at terminal B
The diode will be forward biased and it can be replaced by short circuit.
Net resistance = 
= 10/2 = 5Ω
Case 2: Potential at terminal A < Potential at terminal B
The diode will be reverse biased and it can be replaced by open circuit.
Net resistance=10Ω
1