Question

Two infinitely large plane thin parallel sheets having surface charge densities ${\sigma }_1$ and ${\sigma }_2({\sigma }_2>{\sigma }_1)$ are shown in the figure. Write the magnitudes and directions of the net fields in the regions marked II and III.

Answer 1

The magnitude and direction of electric field in region II is:
$E=\frac{{\sigma }_2}{2{\epsilon }_0}-\frac{{\sigma }_1}{2{\epsilon }_0}=\frac{{\sigma }_2-{\sigma }_1}{2{\epsilon }_0}$ (towards left)
The magnitude and direction of electric field in the region III is:
$E=\frac{{\sigma }_1}{2{\epsilon }_0}+\frac{{\sigma }_2}{2{\epsilon }_0}=\frac{{\sigma }_1+{\sigma }_2}{2{\epsilon }_0}$ (towards right)