The I– V characteristic of a p – n junction diode is shown in figure. Find the approximate dynamic resistance of the p – n junction whena). a forward bias of 1 Volt is appliedb). a forward bias of  2 Volt is applied

a). The current at 1 Volt is 10 mA and at 1.2 Volt is 15 mA . The dynamic resistance in this region is    R=ΔVΔi=(1.2-1)Volt(15-10) mA=0.2Volt5 mA=40Ωb). The current at 2 Volt is 400 mA and at 2.1 Volt it is 800 mA. The dynamic resistance is   R=ΔVΔi=(2.1-2)Volt(800-400) mA=0.1Volt400 mA=0.25Ω