Inside a television picture tube there is a build-up of electrons (charge of 1.602 × 10^–19 c) with an average spacing of 38.0 nanometers between electrons. find the electric field inside the picture tube. (round to three significant figures.)

The magnitude of electric field is produced by the electrons at a certain distance.

E = kQ/r²

where: 
E = electric field produced
Q = charge
r = distance
k = Coulomb Law constant 9 x10^9 N. m2 / C2

Given are the following:
Q = 1.602 × 10^–19 C
r = 38 x 10^-9 m

Substitue the given:
E = 

E = 998.476 kN/C