Question

If a body is charged by rubbing, then its weight:
(A) Remains precisely constant
(B) Increases slightly
(C) Decreases slightly
(D) May increase or decrease slightly

Answer 1

When a body is rubbed, it gets charged. We know a body gets charged either due to gain of electrons or due to loss of electrons. Each electron possesses some mass, and therefore, must have some weight. This change of electrons may result in a change of weight.

Complete Step-By-Step Solution:
We know, in static electricity, an object gets charged by rubbing. This happens due to imbalance of charges on the surface of the material.
We can say an object is charged depending upon the number of electrons gained or lost. When due to rubbing, the number of electrons present on the surface increases, we say that the body Is negatively charged and when after rubbing the number of electrons on the surface decreases, we say that the body is negatively charged,
Thus this gain or loss of electrons indicated the charging of the body.
We know that the mass of an electron is $9.1 \times {10^{ - 31}}Kg$. Due to this, the mass of the body after rubbing will differ from the initial mass of the body. This change in mass causes a change in weight. Therefore, when electrons are gained, the mass of the object increases and when electrons are lost, we say the weight slightly decreases.
Since, the mass of electrons are negligible, therefore, we consider the change to be very slight.
Thus, the mass May increase or decrease slightly
Hence, option (D) is correct.

Note:
We know that there are two types of electricity, one of them is static electricity and the other one is dynamic electricity or current electricity. The difference is due to the motion of charges, in static electricity the charges are at rest and appear on the surface of the body, whereas in current electricity the charges flow inside the conductor and give rise to current.