State Ohm’s law? How can it be verified experimentally? Does it hold good under all conditions? Comment.

According to Ohm’s law:

The electrical current flowing through a conductor is directly proportional to the potential difference across its ends providing the temperature remains same.

R

R= V/I

R is resistance of conductor

V is potential difference

I is current

It can be verified experimentally by following:

1. Set up an electrical circuit consisting of nichrome wire of length ×Y say 0.5m , an ammeter, a voltmeter and four cells of 1.5 V each .

2. Firstly, use one cell as source in the circuit. Note the current in the ammeter and voltmeter reading across the nichrome ×Y in the circuit.

3. Connect two cells in the circuit and note down the reading from the given circuit for the current and potential difference.

4. Repeat the same experiment for three cells and then four cells and note down the reading from Ammeter and Voltmeter.

5. Calculate the value of ratio to each pair of potential difference V and current I.

It is observed that the value of V/I is approximately same for each case and V-I graph obtained is a straight line which verifies Ohm’s law.

No, it doesn’t hold good under all conditions because the value of current is different for different components. Certain components offer an easy path for flow of resistance while others resists the flow.