Forward Resistance: Resistance offered in a diode circuit, when it is forward biased, is called forward-resistance. • DC or Static Resistance: DC resistance can be explained as the ratio of the dc-voltage across the diode to the direct current flowing through it. • AC or Dynamic Resistance: It can be defined as the reciprocal of the slope of the forward characteristic of the diode. It is the resistance offered by a diode to the changing forward current.