Question

A person shuffles across the rug and then place his finger near his friend's nose, causing a small spark that transfers about 10^−9C of charge from the person to his friend. Determine the number of electrons transferred. e=1.6×10^−19C.
Express your answer using two significant figures.

Answer 1

Answer:

$n = \frac{10^{-9}C}{1.6 x10^{-19}C}= 6.25 x10^{9} electrons \approx 6.3 x10^{9} electrons$

Explanation:

For this case we know that the charge associated to the transferred electrons of the small spark is $10^{-19}C$ and we want to find the number of electrons transferred.

From the properties of matter we know that the charge of the electron is

$q_e = |-1.6 x10^{-19}C |= 1.6 x10^{-19}C$

And we know that the total charge is given by this expression:

$Q = n e$

Where Q represent the charge, n the number of electrons and e the charge of the electron.

If we solve for n we got:

$n = \frac{Q}{e}$

And replacing we got:

$n = \frac{10^{-9}C}{1.6 x10^{-19}C}= 6.25 x10^{9} electrons \approx 6.3 x10^{9} electrons$