A metallic object holds a charge of -3.8 x 10^-6C.What total number of electrons does this represent? (e = 1.6 x 10^-19 C is the magnitude of the electronic charge. )

Question

Quizplus · Accepted Answer

We know that the charge on an object is given by Q = Ne, where Q is the charge, N is the number of electrons and e is the charge on an electron.
Rearranging the formula, we get N = Q/e
Substituting the given values, we get 
N = (-3.8 x 10^-6 C) / (1.6 x 10^-19 C)
N = -3.8 x 10^-6 C x (-6.25 x 10^18 / C)
N = 23.75 x 10^12 or 2.4 x 10^13 electrons 
(rounding off to two significant figures)

Therefore, the total number of electrons is 2.4 x 10^13, which is option C.

A Metallic Object Holds a Charge of -3