Read the passage and answer the following questions.
A metal rod held in hand and rubbed with wool will not show any sign of being charged. However, if a metal rod with a wooden or plastic handle is rubbed without touching its metal part, it shows signs of charging. Suppose we connect one end of a copper wire to a neutral pith ball and the other end to a negatively charged plastic rod. We will find that the pith ball acquires a negative charge. If a similar experiment is repeated with a nylon thread or a rubber band, no transfer of charge will take place from the plastic rod to the pith ball.
Assertion (A): All substances readily allow passage of electricity through them.
Reason (R): Substances that allow the passage of electricity through them have electric charges (electrons) that are comparatively free to move inside the material.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A is false but R is true.
Assertion (A) All substances readily allow passage of electricity through them. — False. Only some substances, the conductors, do so. In the passage a nylon thread or a rubber band transfers no charge from the plastic rod to the pith ball; such materials are insulators.
Reason (R) Substances that allow the passage of electricity through them have electric charges (electrons) that are comparatively free to move inside the material. — True. Conductors such as metals have free electrons, which is why the copper wire in the passage carries the charge to the pith ball.
NCERT (2026-27):
Conductors and Insulators – “Some substances readily allow passage of electricity through them, others do not. Those which allow electricity to pass through them easily are called conductors. They have electric charges (electrons) that are comparatively free to move inside the material.”