Suppose a free electron in air is 1.3 cmcm away from a point charge. What minimum charge is needed to cause a breakdown and a spark as the electron moves toward the point charge?

Respuesta :

Answer:

[tex]6.19\times10^{-8}[/tex] C

Explanation:

In order to cause a breakdown and a spark the electric field should be at least

E = [tex]3.3\times10^{6} N/C[/tex]

We know that

a free electron in air is r = 1.3 cm away from a point charge.

[tex]E=k \frac{q}{r^2}[/tex]

[tex]k= \frac{1}{4\pi\epsilon_o}[/tex]

therefore,

[tex]q= \frac{r^2E}{k}[/tex]

substituting the values we get

[tex]q= \frac{(1.3\times10^{-2})^2(3.3\times10^6)}{9\times10^9}[/tex]

= [tex]6.19\times10^{-8}[/tex] C