Question

Example 1.2 If 10º electrons move out of a body to another body
every second, how much time is required to get a total charge of 10
on the other body?
Solution In one second 10 electrons move out of the body. Therefore
the charge given out in one second is 1.6 x 10-19 x 10°C = 1.6 x 10°C.
The time required to accumulate a charge of 1 C can then be estimated
to be 1 C + (1.6 x 10-1°C/s) = 6.25 x 10° s = 6.25 x 10° + (365 x 24 x
3600) years = 198 years. Thus to collect a charge of one coulomb,
from a body from which 10electrons move out every second, we will
need approximately 200 years. One coulomb is, therefore, a very large
unit for many practical purposes.
It is, however, also important to know what is roughly the number of
electrons contained in a piece of one cubic centimetre of a material.
A cuble piece of copper of side 1 cm contains about 2.5 * 10%
electrons.
EXAMPLE 1.2​

Answer 1

Thus to collect a charge of one coulomb, from a body from which 109 electrons move out every second, we will need approximately 200 years.