Question

Two uniformly charged conducting plates are parallel to each other. They each have area A. Plate #1 has a positive charge Q while plate #2 has a charge −3 Q.
Using the superposition principle find the magnitude of the electric field at point P in the gap.
1. E =5Q / εoA
2. E = 4Q/εoA
3. E =3Q/ εoA
4. E =Q/ εoA
5. E =2Q/ εoA

Answer 1

Answer:5

Explanation:

Given

First Plate has a charge of +Q  and area A

Second Plate has a charge of -3 Q and area A

We Know electric Field due to sheet charge is given by

$E=\frac{Q}{2A\epsilon }$

Where Q=charge over the Plate

A=Area of plate

$\epsilon$= Permittivity of free space

Electric Field Due to Positive charge will always be away from it while for negative charge it is towards it.

Net Electric Field at a point between between the Plates is the superimposition of two electric with direction

$E_{net}=\frac{Q}{2A\epsilon }+\frac{3Q}{2A\epsilon }$

$E_{net}=\frac{2Q}{A\epsilon }$

Net electric Field is towards the negative charged plate