Question

The charge density of the middle plane is +14 nC/m2 (nC = "nano Coulomb") and that of the two outer planes is -7nC/m2. Your answers for the electric field must include the correct sign. We choose positive electric field along the positive y-direction.

The figure above shows three very thin parallel planes of charge with equal separation 4 cm between them. The charge density of the middle plane is +14 nC/m2 (nC = "nano Coulomb") and that of the two outer planes is -7nCfm2. Your answers for the electric field must include the correct sign. We choose positive electric field along the positive y-direction. What is the electric field at point A? What is the electric field at point B? What is the electric field at point C? What is the electric field at point D?

Answer 1

A) at point A total electric field=- $\sigma /\varepsilon _0$ +2*$\sigma /\varepsilon _0$ - $\sigma /\varepsilon _0$ = 0 N/C

B) at B= +$\sigma /\varepsilon _0$+ 2* $\sigma /\varepsilon _0$ - $\sigma /\varepsilon _0$ = 2*$\sigma /\varepsilon _0$= 790.96 N/C

C) at C= +$\sigma /\varepsilon _0$ - 2* $\sigma /\varepsilon _0$ - $\sigma /\varepsilon _0$ =-2 * $\sigma /\varepsilon _0$ =  -790 . 96 N/C

D) at D =$\sigma /\varepsilon _0$- 2*$\sigma /\varepsilon _0$+ $\sigma /\varepsilon _0$ = 0 N/C