Question

A polythene piece rubbed with wool is found to have a negative charge of $3\times {10}^{-7}C$ .
(a) Estimate the number of electrons transferred (from which to which?)
(b) Is there a transfer of mass from wool to polythene?

Answer 1

Given,

$q=3\times {10}^{-7}C$

$e=1.6\times {10}^{-19}C$

(a) The number of the electron,

The charge is quantized, $q=ne$

$n=\frac{q}{e}=\frac{3\times {10}^{-7}}{1.6\times {10}^{-19}}$

$n=1.875\times {10}^{12}$ electrons

(b) Yes, mass of electron is transferred.

We know that, $m=9.1\times {10}^{-31}kg$

The transfer of mass, $M=nm$

$M=1.875\times {10}^{12}\times 9.1\times {10}^{-31}$

$M=17.0\times {10}^{-19}kg$