Answer:
+0.3 nC
Explanation:
Assuming that all the static charge could be approximated by a point charge, the electric field created by this charge q, at a distance d from the charge, is as follows:
[tex]E = \frac{k*q}{d^{2}} (1)[/tex]
If this field is strong enough to cause a static spark, it must be at least equal to 3*10⁶ N/C.
If the distance at which we need to find the value of E is d = 1mm = 10⁻³ m, we can solve (1) for q:
[tex]q = \frac{E*d^{2}}{k} = \frac{(3e6N/C)*(1e-3m)^{2}}{9e9 N*m2/C2} = 0.3e-9 C[/tex]
⇒ q = 0.3*10⁻⁹ C = 0.3 nC
