Which one of the following devices is non-ohmic ?
Conducting copper coil
Electric heating coil
Semi conductor diode
Rheostat
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC NDA-1 – 2018
– Conducting copper coil (A) and Electric heating coil (B) (like Nichrome wire) are generally considered ohmic conductors, although their resistance can change with temperature.
– A Rheostat (D) is a variable resistor, but for any fixed resistance setting, it acts as an ohmic resistor.
– A Semiconductor diode (C) is a device that exhibits a highly non-linear current-voltage characteristic. It conducts current effectively in only one direction (forward bias) and only above a certain threshold voltage. Its resistance changes dramatically depending on the applied voltage and direction. Therefore, it is a classic example of a non-ohmic device.
– Non-ohmic devices have resistance that varies with voltage or current.
– Metal conductors are typically ohmic (assuming constant temperature).
– Semiconductor devices like diodes and transistors are typically non-ohmic.