Question

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

Answer 1

q = 3 x 10^-7 C
(a) q = ne, n = $\frac{q}{e}$ = $\frac{3\times {10}^{-7}}{1.6\times {10}^{-19}}$ ≈ 2 x 10¹² (Since polythene has negative charge, electrons are transferred from wool to polythene.)

(b) Yes. Mass transferred = n x m_e = 9.1 x 10^-3 x 2 x 10¹²
= 1.82 x 10^-18 kg