CBSE Class 12-science Answered

An incandescent lamp will not appear to follow Ohm's law , because its resistance changes with temperature.The tungsten filament in the bulb does not follow Ohm's law. As the voltage in the wire filament increases it heats up. The resistance of a wire changes as its temperature changes. Hence the graph of the current and voltage in the wire will curve. The light bulb filament violates Ohm's law. Often if extreme currents are applied to wires, they heat up, change their resistances, and violate Ohm's law.