states that current is proportional to voltage, at constant temperature, . (d)

The graph should be a straight line passing through the origin.

For non-ohmic conductors current is not proportional to voltage, . The graph is non-linear. Examples of non-Ohmic conductors include

as gradient is not constant, or, as gradient is not constant.

Typical graphs can be

y-axis: I, x-axis: V, gradient decreases;

y-axis: V, x-axis: I, gradient increases.

NTC (negative temperaure coefficient): ;

PTC (positive temperature coefficent): .

- Light dependent resistors (LDRs)

brightness , ;

a variation in strain of a material (deformation per unit length due to the effect of an applied load/mass) produces a variation in electrical resistance of material