Page 35 - Basic Electrical Engineering

higher potential to lower potential is similar to the flow of water from a
higher level to a lower level.

1.6 OHM’S LAW

George Simon Ohm found that the voltage, V between two terminals of a
current-carrying conductor is directly proportional to the current, I flowing

through it. The proportionality constant, R is the resistance of the conductor.
Thus, according to Ohm’s law

This relation will hold good provided the temperature and other physical
conditions do not change.

Figure 1.1 (a) Shows linear relationship between V and I; (b) V−I characteristics for different values
of R

Ohm’s law is not applicable to nonlinear devices like Zener diode, voltage

regulators, etc. Ohm’s law is expressed graphically on V and I-axies as a
straight line passing through the origin as shown in Fig. 1.1 (a).

The relationship between V and I have been shown for different values of
R in Fig. 1.1 (b). Here in V = RI, R indicates the slope of the line. The more

the value of R is, the more will be the slope of the line as shown in Fig. 1.1
(b).