Ohm’s Law

Ohm’s law states that, “At constant temperature,the amount of current passing through a metabolic conductor is directly proportional to the potential difference across the conductor.”

i.e., Current(I) ∝ potential difference
or, I ∝ V
or, V ∝ I
Here, R is a constant called resistance of the conductor.

The graph between V and I is as shown in the figure below.

Experimental verification of Ohm’s law:


Consider an electric circuit having a battery (B) as a switch, resistance (R), rheostat (Rh), closed key (K) voltmeter (V) and ammeter (A) as shown in figure. Here, voltmeter measures potential difference across the resistance of the circuit and the ammeter measures the flow of current flowing through the circuit.

Now, close  the switch and measures the reading of the ammeter and the voltmeter. Now changing Rheostat, we measure the different value of current and the voltage as shown in table.

SN Potential difference (V) Current (I) V/I
1.           V1 I1 V1/I1
2.           V2 I2 V2/I2
3.           V3 I3 V3/I3

Here, the ratio of V ⁄ I always found to be constant.
i.e, V ⁄ I=Constant
∴ V ∝ I
Hence,  Ohm’s law is verified.

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