dVdI
dVdI is commonly written as dV/dI and denotes the differential of voltage with respect to current along an I–V characteristic. In electronics the quantity is also called the differential resistance and is the reciprocal of the differential conductance (Gd = dI/dV). While some informal texts may render it as dVdI, the standard notation uses the division to indicate a derivative.
Mathematically, if a device has a voltage V that depends on current I, V = V(I), then dV/dI
Measurement and use in circuit analysis rely on small-signal or incremental modeling. By applying a tiny perturbation
Examples of relevance include diode forward bias, where Rd = nVt/I decreases as current increases, and superconducting