PH 102 Lecture Notes - Lecture 9: Ohmic Contact, Electrical Resistance And Conductance, Voltage
Document Summary
The resistance of a conductor is defined as. In metals the voltage is proportional to the current over a wide range of current and voltage and r is constant. In this case the equation above is referred to as ohm"s law". In some materials or devices the voltage is not proportional to the current and the material or device is said to be non-ohmic. The equation above still applies, but r depends on the values of i and v. (note: in circuits we often write the potential difference v between two points as just. V, so that we might write v = ir. ) In an ohmic device (constant r) the i-v curve would be linear, and in a non-ohmic device the i-v curve would be nonlinear. An example of a non-ohmic device would be a diode, in which the current flows more easily in one direction than the other.
