Question

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.)

Answer 1

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 = $\frac{( 1.602 x 10^{-19} )( 9.0x10_{9} )}{(38x10^{-9}) ^{2} }$

E = 998.476 kN/C

Answer 2

The answer is  997,000 N/C