Q 1.11(a): A polythene piece rubbed with wool is found to have a negative charge of 3\times 10^{-7}. (a) Estimate the number of electrons transferred (from which to which?)

Answers (1)
H Harsh Kankaria

Clearly, polyethene being negatively charged implies that it has an excess of electrons(which are negatively charged!). Therefore, electrons were transferred from wool to polyethene.

Given, Charge attained by polyethene = -3\times 10^{-7} C

We know, Charge on 1 electron = -1.6\times10^{-19} C

Therefore, the number of electrons transferred to attain a charge of -3\times 10^{-7} = 

\frac{-3\times 10^{-7}}{-1.6\times10^{-19} C} = 1.8\times10^{12} electrons.