Elementary charges

1. Dec 30, 2006

Fusilli_Jerry89

1. The problem statement, all variables and given/known data
1) How many electrons make up a charhe of 1 mu C?

2)What is the magnitude of the force a 10-mu C charge exerts on a 3.0-mC charge 2.0 m away? (1 muC=10^+/-6C , 1 mc=10^+/-3C)

2. Relevant equations
FE=(kQQ)/d^2

3. The attempt at a solution
1) (10E-6 C)/(1.6E-19)
I got 6.2E13 but the book says a micro columb is 1.0E-6, and the other book I have says it's 10E-6. Which is it?

2)FE=[(9.0E9)(1E-4)(0.03)]/4
=6750 N
The book says the 10-mu C charge is 10E-6 and the 3.0-mC charge is 3.0E-3.

I'm confused.

2. Dec 30, 2006

Staff: Mentor

I think it's just a limitation of the notation for exponential notation when not using LaTex or some other math typesetting tool.

A microColoumb is definitely $$1*10^{-6} C$$

And when you try to write exponential notation without using math typesetting, you can try to write it either of the ways you listed.

3. Dec 30, 2006

Saketh

That's not right.
Once you figure out how to make the microcoulomb/millicoulomb conversion, you won't make the same mistake again. Don't mix up microcoulombs (E-6) and millicoulombs (E-3)!

$$10 \mu\rmmath{C} = 10 \times 10^{-6} C$$
$$3 \rmmath{mC} = 3 \times 10^{-3} C$$

Last edited: Dec 30, 2006
4. Dec 30, 2006

blastyournos

well if you use scientific notation its gotta be 1.0E-6, cant have anything more than 9 as the base.