Mass and charge are two different properties associated with a body. Which of the following is true?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → When a body is charged, its mass changes slightly.
A body gets charged when electrons move to it or away from it. It becomes positive by losing some of its electrons. It becomes negative by gaining electrons.
Option (1) When a body is charged, its mass changes slightly. — Correct. Every electron has a mass of \( 9.11\times10^{-31}\,\mathrm{kg} \). So a body that gains electrons becomes slightly heavier, and one that loses electrons becomes slightly lighter. The change is tiny because only a very small fraction of the electrons in the body moves.
Option (2) When a body is charged, the mass of the body is unchanged. — Incorrect. Electrons carry the charge, and electrons have mass. So the mass cannot stay the same. It changes by only a very small amount.
Option (3) Charging of a body requires no work. — Incorrect. Charging separates positive and negative charges, which attract each other. So work has to be done against this attraction, as in rubbing a glass rod with silk.
NCERT (2026-27):
Electric Charge – “… In solids, some of the electrons, being less tightly bound in the atom, are the charges which are transferred from one body to the other. A body can thus be charged positively by losing some of its electrons. Similarly, a body can be charged negatively by gaining electrons. … Also the number of electrons, that are transferred, is a very small fraction of the total number of electrons in the material body.”