Case: Read the passage and answer the following questions.
Historically the credit for the discovery of the fact that amber rubbed with wool or silk cloth attracts light objects goes to Thales of Miletus, Greece, around 600 BC. The name electricity is coined from the Greek word ‘electron’ meaning amber. Many such pairs of materials were known which on rubbing could attract light objects like straw, pith balls and bits of paper. For example, cut out long thin strips of white paper and lightly iron them. Take them near a TV screen or computer monitor. We can see that the strips get attracted to the screen. In fact, they remain stuck to the screen for a while.
What happens when a plastic rod rubbed with fur and a glass rod rubbed with wool are brought close to each other?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → They attract each other.
Option (1) They attract each other. — Correct. By convention the glass rod rubbed with wool becomes positively charged and the plastic rod rubbed with fur negatively charged. Unlike charges attract, so the two rods pull towards each other.
Option (2) They repel each other. — Incorrect. Repulsion happens between like charges, such as two glass rods rubbed with wool. These two rods carry opposite kinds of charge.
Option (3) A chemical reaction occurs. — Incorrect. Rubbing only transfers electrons between the surfaces. When the charged rods are brought near each other, only an electric force acts between them.
Option (4) No visible reaction occurs. — Incorrect. Both rods are charged, and the force between them is strong enough to move a freely suspended rod towards the other.
NCERT (2026-27):
Electric Charge – “… On the other hand, the plastic rod attracts the glass rod … and repel the silk or wool with which the glass rod is rubbed. The glass rod repels the fur.”