Question

In a series of oil-drop expiriments, the charges measured on the oil drops were -3.20 x 10^-19 C , -6.40 x 10^-19 C , -9.60 x 10^-19 C , and -1.12 x 10^-18 C . What is the smallest difference in charge between any two drops? If this is assumed to be the charge on the electron, how many excess electrons are there on each drop?

Not sure how to find the excess electrons on each drop. And why is the smallest difference found by dividing -3.20 x 10^-19 C/2 = -1.6 x 10^19C?

Answer 1

Since all the drops are in having cgarges in multiple of charge of electron that is minimum difference will be of 1 electron and since electron have charge of 1.6 * 10^-19 C so it'll be the smallest difference

since the charge on the electron is -1.6 * 10^-19 C we can find excess electrons by finding out how many electrons are there,

number of electrons can be taken out by dividing total charge by charge on electron

and excess electron will be total number of electron - 1

so for,

-3.20x10^-19 C = 1 excess electrons
-6.40x 10^-19 C = 3 excess electrons
-9.60x10^-19 C = 5 excess electrons
-1.12x10^-18 C = 6 excess electrons