A polythene piece rubbed with wool is found to have a negative charge of `3 xx 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?

Explanation

(a) Since the polythene piece acquires a negative charge (q) on rubbing with wool, electrons are transferred from wool to polythene. If n is the number of electrons transferred, then
`q="ne"` or `n=(q)/(e )=(3xx10^(7)C)/(1.6xx10^(-19)C)=1.875xx10^(12)`
(b) Mass transferred from wool to polythene is
`(1.875xx10^(12))(9.1xx10^(-31)kg)=1.7xx10^(-18)Kg`
of course, this mass is negatively small.