Question

Which of the following is an ohmic conductor
A. Transistor
B. Vacuum tube
C. Electrolyte
D. Nichrome wire

Answer 1

Hint:An ohmic conductor can be explained as a conductor that follows or obeys the Ohm’s Law which states that the potential difference across the two ends of a resistor is directly proportional to the current passing through the resistor. Hence, the graph of $V\to I$ for ohmic conductors will be a straight line passing through the origin.

Complete answer:
The Ohm’s Law states that “The potential difference $V$ that is applied between the two ends of a conductor is directly proportional to the current $I$ passing through the conductor.” The proportionality constant is known as the resistance $R$ of the circuit. Hence, Ohm's Law is expressed as $V=IR$ , which is similar to the equation of line $y=mx$ that indicates a straight line passing from origin.

Now, the conductors that follow the Ohm’s Law and whose resistance remains constant with temperature are known as Ohmic conductors and the conductors that don’t follow the Ohm’s Law and whose resistance might change on change in temperature are known as

Non-Ohmic conductors: As we know in a transistor, up to a fixed value of voltage (known as the threshold voltage) there is very little amount of current observed. And after the threshold voltage, there is a steep rise in the current. Hence, the relation of voltage and current is not linear. Hence, the transistor is a non-ohmic conductor.

Vacuum does not contain any charged particles to conduct electricity. Hence, the vacuum acts as an insulator. The electrolyte can be both Ohmic and Non-ohmic. We can say on a general basis if an electrolyte is an ohmic conductor or not. The Nichrome wire is an alloy of Nickel, Chromium and some amount of iron, which is used as a resistance wire in many appliances.

Hence, the correct answer is option D.

Note: We need to understand here that electrolyte is a general term and we cannot decide if it will be ohmic or non-ohmic specifically. There are many electrolytes available, and out of them certain show ohmic nature, whereas others show non-ohmic nature. For example, copper sulphate solution acts as an ohmic substance and follows Ohm's Law and substances like Hydrochloric acid or simple water acts as a Non-Ohmic substance.