Charge of Mass

[rhaylor]

I'm just getting started here and need a little help. Need a general method to figure problems like these:

If a drop of mass 1.1 X 10 ‾14 kg remains stationary in an electric field of 1.68 X 10 N/C:

(a) What is the charge of this oil drop?

(b) How many extra electrons are on this particular oil drop (given the presently-known charge of the electron)?

Any help is deeply appreciated.

rhaylor :redface:

[ehild]

If a drop of mass 1.1 X 10 ‾14 kg remains stationary in an electric field of 1.68 X 10 N/C:




Well... What forces act on that oil drop? It is here on the Earth and it has mass, so it can not avoid gravity. And it is in an electric field, and it has charge, although unknown yet, but is does not move so the forces must cancel each other....

ehild