The magnitude of the electric field vector on the ground is 100 N/C and it's direction towards the ground and perpendicular to it . The magnitude decreases as we go further from the ground till it reaches 20N/C at height 1400m.
Calculate the average volume charge density (ρ) of the air layer between the ground and this height.

Question

The magnitude of the electric field vector on the ground is 100 N/C and it's direction towards the ground and perpendicular to it . The magnitude decreases as we go further from the ground  till it reaches 20N/C at height 1400m.
Calculate the average volume charge density (ρ) of the air layer between the ground and this height.

vincent-lyon.fr · Answer

Do you know Maxwell-Gauß equation:

$\vec\nabla.\vec E = \rho/\epsilon_o$

y2o2 · Answer

Actually No , I still haven't studied the all the Maxwell equations.
I studied Gauss law , but I didn't study the divergence form of it.
I don't know if it can be solved by Gauss law.
$${\int\limits_{}^{} E.dA = } {Q \over \epsilon_o}$$

vincent-lyon.fr · Answer

Ok, now you have to choose a Gaussian surface that goes from the altitude O to 1400 m.

Work out flux of E, then you will get Q.

Divide by volume and you will get $\rho$.

y2o2 · Answer

I thought of this , but I couldn't do it. because I don't know the right G.surface to choose , and also I wasn't given any area to find a volume

vincent-lyon.fr · Answer

Use any cylinder of base A and height h = 1400 metres.

Volume inside cylinder will be: V = A.h