# Need help with Force between electrons

#### Aprilshowers

The electric charge of an electron is -1.6 X 10 to the -19 power C.
What is the force exerted between two electrons separated by one meter?

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#### Nylex

Use Coulomb's law:

$$F = \frac{q_{1}q_{2}}{4\pi\epsilon_{0}r^2}$$

$q_{1}, q_{2}$ are the charges, $\epsilon_{0}$ is the permittivity of free space and r is the separation.

#### whozum

If you havent dealt with k in its explicit form, use

$$F = \frac{kq_1q_2}{r^2} \ with \ k = 9.0 \times 10^9$$

$$\epsilon_0 = 8.85 \times 10^{-12}$$

#### Pyrrhus

Homework Helper
To avoid confusions

$$|\vec{F}_{e}| = k_{e} \frac{|q_{1}||q_{2}|}{r^{2}_{1-2}}$$

#### Aprilshowers

Math help on previous force problem

I guess I need some Math help. My book says the formula is
F = k q^1 q^2
d^2
So when I plug in my information, my distance is 1, so I get down to:
F = 9.0 X 10^9N X m^2/C2 times (1.6 X 10^-19C)^2

I cannot figure out how to work with the negative exponents that
are so big. My calculator keeps throwing me back to the format
the problem is in. Can anyone provide some math help?

#### Nylex

What do you mean? Do you not know how to enter powers on your calclulator?

#### Aprilshowers

I do have calculator problems! I played around with the calculator until
I think I have the answer:
2.304 X 10^-28
Does that look right?

#### Nylex

Aprilshowers said:
I do have calculator problems! I played around with the calculator until
I think I have the answer:
2.304 X 10^-28
Does that look right?
Yep, it looks ok. Remember the units though!

Thank you!

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