electric field! i beg you! please help me with this!?

Question

question:

1.) A point charge q produces an electric field of magnitude 90.5 N/C at a distance of 1.68 m. if the field is directed toward the charge, what is the value of q?

help me, please???.............

Answer 1

We take the equation for the magnitude of the electric field of the point charge:
E = q / 4πε sqr(r) and q = 4πε sqr(r) x E =
= 4 x π x 8.85 x 10^─12 C/Nm2 x sqr(1.68 m) x 90.5 N/C = 2.84 x 10^─8 C = 28.4 nC

Answer 2

the above looks about right, i cant think of any other formula u could use.
btw k = 1/(4*pie*r^2*(8.82*10^-12))

sub. in r, then u can work out the exact value of the charge from the above guys answer. 8.82*10^-12 is just the permitivitty of free space, which is why it is used in the equattionm for k.

Answer 3

Begging? Help's on the way:
E = F/q
Don't use that equation; use:
E = kq/r^2
90.5 = kq/(r^2)
q = 90.5(1.68)^2/k