The net electric charge of a conductor does not change when:

While doing his experiment,Millikan one day observed the following charges on a single drop:
$(i)$ $6.563 \times 10^{-19} \ C$
$(ii)$ $8.204 \times 10^{-19} \ C$
$(iii)$ $11.50 \times 10^{-19} \ C$
$(iv)$ $13.13 \times 10^{-19} \ C$
$(v)$ $16.48 \times 10^{-19} \ C$
$(vi)$ $18.09 \times 10^{-19} \ C$
From this data,the value of the elementary charge $(e)$ was found to be:

$A$ body can be negatively charged by which of the following methods?

Which instrument is used to detect the charge on a body? Explain it with a diagram.

The vehicles carrying inflammable fluids usually have metallic chains touching the ground:

Describe the activity to construct a simple electroscope.