Circuit to verify Ohm's Law

Ohm's Law states that the current passing through a conductor (or a resistor) at constant temperature is directly proportional to the potential difference between its ends. Thus Ohm's law implies, ie, The constant is known as electric resistance. Therefore: Thus the ohm is the resistance of a device such that a potential difference of one volt is applied to its ends, a current of one ampere flows through it.

Limitations of Ohm's Law 1. All physical conditions (eg, temperature, length, etc) must remain constant.

2. It does not apply to all conductors, eg, radio valves, transistor rectifiers, etc (known as non-ohmic conductors).

An experiment to verify Ohm's Law 1. Connect the circuit as shown in Figure 1.

2. Obtain a series of pairs of readings of the current I through the resistor R (a sample of alloy wire with small temperature coefficient), and the corresponding readings of the voltage V by varying the resistance of the rheostat.

Note: Rheostat is a resistance whose value can be varied.