Answer to Question #299398 in Physics for yumi

Question

When a glass is rubbed with a silk cloth, the rod acquires a charge of magnitude 3.45 nC. (a) Did the glass rod gain or lose electrons/ (b) How many electrons were transferred during the process? (c) What is the change in the mass of the glass rod? (d) What is the change in the mass of the silk cloth?

Answer 1

Given:

$q=3.45\;\rm nC=3.45*10^{-9}\: C$

$e=1.6*10^{-19}\rm\: C$

$m=\rm 9.1*10^{-31}\: kg$

(a)  glass rod lose electrons.

(b)

$$N=\frac{q}{e}=\frac{3.45*10^{-9}}{1.6*10^{-19}}=2.16*10^{10}$$

(c)

$$\Delta m=N m\\ =2.16*10^{10}*9.1*10^{-31}=1.96*10^{-20}\:\rm kg$$