a. How many electrons are needed to make up a total charge of −1 C? Show your work.

b. There are roughly 1023 atoms (= “Avogadro’s number”) in a typical object of centimeter scale. If you rub a balloon against your hair until the balloon has a negative charge of 1 C, estimate what fraction of the atoms in the hair have contributed an electron to charge the balloon.

Question

a. How many electrons are needed to make up a total charge of −1 C? Show your work.

b. There are roughly 1023 atoms (= “Avogadro’s number”) in a typical object of centimeter scale.  If you rub a balloon against your hair until the balloon has a negative charge of 1 C, estimate what fraction of the atoms in the hair have contributed an electron to charge the balloon.

gebooors · Answer

A) Charge of an electron is 1.6 * 10^-19 C.
Number of electrons is  1/1.6*10^-19 = 6.25*10^18 electrons.

Let's assume that one atom gives one electron.
For transferring charge of 1 C, 6.25* 10^18 atoms gives electrons.

If we divide this by Avogadro number, we get 1/96000
It is close 0.00001 or 0.0001 per cent.

More accurate answer you should think how long part of a hair in cm
Is contact with the balloon and how many hairs.

Then the fraction is much smaller