Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): When no electric field is applied, a metallic conductor carries no net current.
Reason (R): In the absence of an electric field, the free electrons in a conductor are at rest.
In the light of the above statements, choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) is true but (R) is false.
Assertion (A) When no electric field is applied, a metallic conductor carries no net current. — True. Without a field, the free electrons move about by thermal motion. After each collision with the fixed ions, an electron comes out in a random direction. At any instant, as many electrons travel in one direction as in the opposite direction. So no net charge crosses any section of the conductor.
Reason (R) In the absence of an electric field, the free electrons in a conductor are at rest. — False. The free electrons are in random thermal motion even when no field is applied. Their velocities point in all directions, so only their average velocity is zero.
NCERT (2026-27):
Electric Currents in Conductors – “Consider first the case when no electric field is present. The electrons will be moving due to thermal motion during which they collide with the fixed ions. An electron colliding with an ion emerges with the same speed as before the collision. However, the direction of its velocity after the collision is completely random. At a given time, there is no preferential direction for the velocities of the electrons. Thus on the average, the number of electrons travelling in any direction will be equal to the number of electrons travelling in the opposite direction. So, there will be no net electric current.”