Question

From the graphs given below, choose the ohmic and non-ohmic curve.
i)

ii)

iii)

iv)

• A. All are Ohmic resistance.
• B. All are non-ohmic resistance.
• C. I and III are ohmic resistance and II and IV are non-ohmic resistance.
• D. I and III are non-ohmic and II and IV are ohmic resistance.

Answer 1

The correct option is C

I and III are ohmic resistance and II and IV are non-ohmic resistance.

Ohm's law states that the current flowing in a conductor is directly proportional to the potential difference applied across the conductor provided the physical conditions and temperature remains constant.
Ohmic resistors are the ones that follow Ohm's law. Thus, the current (I) passing through the conductor is directly proportional to the potential difference (V) applied. The V-I graph for an ohmic resistor will be a straight line passing through the origin, as the quantities are directly proportional.
Non-ohmic resistors are the ones do not follow Ohm's law. Thus, the current (I) passing through the conductor is not directly proportional to the potential difference (V) applied. The V-I graph for an ohmic resistor will not be a straight line as the quantities are not directly proportional.
Hence, among the given graphs, graph I and III represents ohmic resistors.