# Electric Field charge calculation

1. Sep 3, 2005

Hi

This is a homework question, but Im trying to see if Ive got the format correct. Two protons are separated by 3.80 x 10-10m. Find the electric force exerted by one proton on the other

........................... |q1||q2|
So Ive got Fe =.. ke ------------
............................... r^2

Im told the proton charge is +1.6021917 x 10-19

so................... 2.5667E-38
............ke * .. -------------
...................... 1.444 E-19

then...... ke * 1.7775 E -19

then 1.5979 E-9 as the final answer?

Is there some way to write equations and allow whitespace?

2. Sep 4, 2005

### Nam_Sapper

$F = \frac{2.5667E-19}{1.444E-19}$

Okay I wrote this by typing this: [ itex ] F = \frac{2.5667E-19}{1.444E-19} [ /itex ] (take out the spaces in the tags with the square brackets.)

$$F_{total} = K_e \frac{Q_1 Q_2}{r^2}$$

This was written with this:[ tex ] F_{total} = K_e \frac{Q_1 Q_2}{r^2} [ /tex ] (again take out the spaces)

Last edited: Sep 4, 2005
3. Sep 4, 2005

Hey thats too cool $F_{total} = K_e \frac{q_1 q_2}{r^2}$

its not working on preview, anyone know if the result is correct?

also, would 15 pounds of electrons have enough field energy to support the mass of the earth? It calculates out to be many times more, but if thats the case? batteries can still be improved to store more energy

This is my first Physics for electricity/Magnetism course

4. Sep 4, 2005

### Kazza_765

Without doing any equations, I'm pretty sure 15 pounds of electrons would be more than enough to support the Earth. What you mean by support the earth though, I'm not sure. The electromagnetic force is some 38 orders of magnitude (or thereabouts) stronger than gravity. You would have some problems though:
-How do you get 15 pounds of electrons without any protons
-Given that the electromagnetic force is so strong, how do you contain them, since they will want to repulse each other.
- The overall net charge on the earth (I'm assuming) is probably very close to zero, so the net force on the earth is going to be very small.
But yeah, the electromagnetic force is much, much stronger than gravity, its just that in everyday life, almost everything has the same number of positive and negative charges, so it cancels out.

5. Sep 4, 2005