Electric charge equally distributed in rice grains

[martinskibg]

Homework Statement

How many rice grains are needed for an electric charge of a certain strength (I don't remember the value now but is it really relevant?) to be equally distributed amongst them?

Homework Equations

I hope you can answer that :)

The Attempt at a Solution

I can only guess. Is there a formula for this? Whats the logic behind this. I was given such a question on a test.

 

[ideasrule]

The exact value of the charge is very important. If it turns out to be precisely 3 times the charge on an electron, we know that 3 rice grains are needed.