Which of the following is a non-ohmic device?WireDiodeRheostatCopper coil

The non-ohmic device among the options given is the Diode.

Here's why:

1. Ohmic devices are those that follow Ohm's Law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points.

2. A wire, rheostat, and copper coil are all examples of ohmic devices because they follow Ohm's Law. Their resistance remains constant as the voltage across them changes.

3. A diode, on the other hand, is a non-ohmic device. It does not follow Ohm's Law. Its resistance changes with the change in voltage across it. In a diode, current does not flow until a certain threshold voltage is reached. Once this threshold is crossed, current flows very easily. This is why the diode is considered a non-ohmic device.