Question

A device that doesn't obey Ohm's law is a

a. copper wire

b. silver bar

c. light bulb

d. resistor

Answer 1

Ohms law is obeyed when the voltage is proportional to the current in the circuit. The change in voltage per current is always constant. The slope is constant for V_I graph.

Copper wire, silver bar and resistors are ohmic materials while light bulb is not because, light bulb emits light by heat energy produced in the thin filament. As the number of hours of usage is done, the resistance of the light bulb changes. The voltage to current fluctuate day by day when it used continuously.