If your body has acquired a charge of -15 microcoloumbs how many excess electrons has it acquired?

Question

HELP!

Answer 1

9.375*10^13 electrons have a charge of

9.375*10^13*(1.602*10^-19) = 0.00001501875 Coulomb

the ratio of "this charge" to 15uc is:

0.00001501875/(15*10^-6) = 1.00125

This is close enough! Ali answer is good enough.

If someone picks a random amount of charge out

of the blue "-15uc", you can't, necessary, fit a whole number

of electrons into it.

Answer 2

No charge = 0 coulombs

Charge on one electron = - 1.6 x 10-19 coulombs

* Micro = x10^-6

Therefore (-15x10^-6) / (-1.6 x 10-19) =

9.375 x 10^13 electrons

Obviously you can't get 0.375 of an electron, so use your data sheet's estimation of the charge on an electron. You should get a whole number.

Answer 3

Simply use a conversion factor made from the charge on a single electron.  To two significant digits, the number of electrons is given by:

15 x 10^-6 C x (1 e- / 1.6 x 10^-19 C) = 9.4 × 10^13

That's a boatload of electrons, but they can easily fit on the head of a pin.

======== Follow up =========

Ali has totally missed what the number in scientific notation actually represents.  There isn't 0.375 electron.  She's missed the "x10^13" part of the number.

Look at it like this:

9.375 x 10^13 electrons is the same as

93,750,000,000,000 electrons

Clearly, there is no fractional part of an electron.