Question

A 7.02 μC point charge is at the center of a cube with sides of length 0.675 m .

Part A - What is the electric flux through one of the six faces of the cube?

Part B - How would your answer to part A change if the sides were of length 0.210 m ?

Part C - explain

Answer 1

q = 7.02 μC = 7.02 X 10^-6 C

L = length 0.675 m

Part A )

using flux equation

= q / _o

the same way, the flux of the cube is

= q / 6_o

= 7.02 X 10^-6 / 6 X 8.85 X 10^-12  

= 0.132203 X 10^-6 Nm²/C

Part B )

the same way, the flux of the cube is

= q / 6_o

= electric flux

q = charge

_o = permittivity of free space

so this above expression says that the flux doesn't depend on length.

so the flux is the same when the length is even changed

so the flux is the same when L = 0.21 m also

= 0.132203 X 10^-6 Nm²/C

Part C )

so the flux throughout the crystal won't change.

because

the flux doesn't depend on length.