Question

Which one is a non-ohmic resistance?

Options

• constantan wire

• electric bell

• coil of heater

• eureka wire

Answer 1

Electric bell

Explanation:

An electric bell contains an electromagnet, which is a non-ohmic device because it does not obey Ohm's law. Constantan wire and eureka wire are alloys whose resistance remains almost constant, so they are ohmic. A heater coil is made of a metallic alloy and behaves as an ohmic resistor at constant temperature.