# Homework Help: Electric field problem (never mind )

1. Feb 4, 2010

### Chiborino

1. The problem statement, all variables and given/known data
What magnitude charge creates a 8.1 N/C charge at 3.00m away?
(Masteringphysics wants it in nC)

2. Relevant equations
E=KQ/d^2

3. The attempt at a solution
E=KQ/d^2 $$\rightarrow$$ Q=E*d^2/K

E=8.10 N/C
K=8.99*10^9Nm^2/C^2
d=3.0m

Q=$$\frac{(8.10 N/C)(9.0m^2)}{(8.99*10^9 Nm^2/C^2)}$$= 8.1*10^-9C

Converted to nC, the answer should be 8.1*10^-3, shouldn't it? I've also tried 10^-15 in case I was being dumb with the exponent rules. I also converted the 8.1 N/C into N/nC and received the same answer, yet MasteringPhysics keeps saying it's wrong and I can't seem to find my source of error

EDIT: delete this thread, I just realized that "nano" is 10^-9, not -6. Answer was 8.1 nC. Whoops. ._.

Last edited: Feb 4, 2010