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

When N no. of electron get transferred from wool to polythene, it gets a negative charge, q = - Ne (Where e = magnitude of charge of one electron)
`therefore N =-q/e`
`=-(-3.2 xx 10^(-7))/(1.6 xx 10^(-19))`
`N = 2 xx 10^(12)`
Here, N no. of electrons are transferred from wool to polythene. Hence, wool loses mass of N no. of electrons and polythene gains mass of N no. of electrons. Thus, mass transferred in this process.
`= Nm_(e)`
`=2 xx 10^(12) xx 9.1 xx 10^(-31)` kg
`=1.82 xx 10^(-18)` kg
(Above mass is negligibly small)