Electrical charge problem (need assurance on an answer)

[AyooNisto]

Homework Statement

Dry air will break down and generate a spark if the electric field exceeds about 3.0\times 10^6 N/C How much charge could be packed onto a green pea (diameter 0.81cm ) before the pea spontaneously discharges?

Homework Equations

E = kQ/r^2
Q = Er^2/ k <-------this is the equation to use I believe

The Attempt at a Solution

(3*10⁶)(3.81*10^-3)²/8.988*10⁹

resulting in an answer of 4.845160214*10^-9 = 5*10^-9

does this look right to you guys?

 

[ehild]

The radius is not 3.81*10-3 m. Check.

ehild

 

[AyooNisto]

figured it out, the diameter is .405
so the answer would be
(3*106)(4.05*10-3)2/8.988*109 = 5.5 *10^-9
Thank you for your help

The radius is not 3.81*10-3 m. Check.

ehild