# A small bulb has a resistance of 2 ohm when it is cold. It draws 0.4 ampere current from a source of4V and then starts glowing. Calculate the resistance when it is glowing

Given,

Resistance (R cold) = 2 Ohm

Current (I) = 0.4 Ampere

Voltage (V) = 4V

Let us calculate the resistance when it is glowing by using Ohm’s law.

According to Ohm’s law,

V = I x R

$$R = \frac{V}{I}$$

Substituting the values in the above equation, we get

R = 4/0.4

R = 10 Ohm