I need to calculate the closest two parallel plates can get before they spark

Question

I have the voltage, and will use E=V/dist (rearranged) to get the distance.

I THINK the field strength value I should use is 3x10^-6 Vm^-1.

No other info is given in the question, so am i close?

Thanks

Answer 1

that's 3x10^6, not -6

Answer 2

Dry air has a breakdown voltage of about 30Kv/inch, so your breakdown voltage is about three times higher than that. However, knowing what I know, I would stick with about 30kv/inch