Electric charge and fields: uniform electric field

[Dx]

A force of 6N acts on a charge of 3 microC when placed in a uniform electric field. what is the magnitude of the electric field?

I have
E = k(Q/r^2... k=9x10^9 * (Q,charge=3x10^-9) / (?)^2

ths can't be the right formula caus e wheres r^2?
Dx [?]

[Tom Mattson]

Originally posted by Dx
A force of 6N acts on a charge of 3 microC when placed in a uniform electric field. what is the magnitude of the electric field?

I have
E = k(Q/r^2... k=9x10^9 * (Q,charge=3x10^-9) / (?)^2

ths can't be the right formula caus e wheres r^2?
Dx [?]

You're right, it is not the correct formula. The formula you quoted is only for an electric field due to a point charge. That's not what you have here; you have a uniform electric field.

The relationship between force and electric field is F=qE.