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.
Bodies like glass or plastic rods, silk, fur and pith balls acquire ……… on rubbing.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → an electric charge
Option (1) a potential energy — Incorrect. A rubbed rod attracts bits of paper through an electric force. This electric force needs a charge on the rod. Stored energy alone cannot attract the paper.
Option (2) a kinetic energy — Incorrect. The rod is at rest after rubbing, so it has no kinetic energy, yet it still attracts light objects.
Option (3) an electric charge — Correct. On rubbing, some electrons are transferred from one body to the other, so one body becomes positively charged and the other negatively charged. Such electrified bodies attract light objects.
Option (4) a chemical energy — Incorrect. Rubbing does not change the substance of glass, silk or fur; the bodies only gain or lose a small number of electrons.
NCERT (2026-27):
Electric Charge – “… It was concluded, after many careful studies by different scientists, that there were only two kinds of an entry which is called the electric charge. We say that the bodies … are electrified. They acquire an electric charge on rubbing.”