Consider the following statements 1. Ohm’s law holds good when the temperature is changed. 2. Ohm’s law holds when the temperature of the conductor remains constant. 3. Ohm's law is an assumption that current through a conductor is directly proportional to the potential difference applied to it when temperature is constant. Which of the following statements is INCORRECT?

Consider the following statements 1. Ohm’s law holds good when the temperature is changed. 2. Ohm’s law holds when the temperature of the conductor remains constant. 3. Ohm's law is an assumption that current through a conductor is directly proportional to the potential difference applied to it when temperature is constant. Which of the following statements is INCORRECT? Correct Answer Only 1

CONCEPT:

Ohm’s law:

• At constant temperature, the potential difference across a current-carrying wire is directly proportional to the current flowing through it.

          i.e. V = IR

          Where V = potential difference, R = resistance and I = current.

EXPLANATION:

• Ohm 's law is not applicable at very low and very high temperatures because as the temperature  increases, the ions inside the metal acquire energy and start oscillating about their mean positions.
• These vibrating ions collide with the electrons.
• Hence the resistance increases with an increase in temperatures. Therefore option 1^st is incorrect.
• If the physical conditions of the conductor (length, temperature, mechanical strain etc.) remain constant, then the current flowing through the conductor is directly proportional to the potential difference across it’s two ends i.e. I ∝ R ⇒ V = IR where R is a proportionality constant, known as electric resistance.
• Therefore, option 2^nd and 3^rd is correct.