Question

Figure shows the portions of two infinite parallel non-conducting sheets having the magnitude of the surface charge densities ${\sigma }_{\left(+\right)}=6.8\mu C/m^2$ and ${\sigma }_{\left(-\right)}=4.3\mu C/m^2$ for the positively and negatively charged sheets, respectively. Find the electric field $\overrightarrow{E}$ between the sheets

• A. $6.3\times 10^{5}N/C$ towards right
• B. $6.3\times 10^{5}N/C$ towards left
• C. $1.41\times 10^{5}N/C$ towards right
• D. $1.41\times 10^{5}N/C$ towards left

Answer 1

Answer: (C)

The electric field due to sheet of positive charge will be from left to right (along positive direction) and that due to sheet of negative charge will be from right to left (along negative direction).
$\therefore E=\frac{{\sigma }_{(+)}}{2{\epsilon }_0}+\left[-\frac{{\sigma }_{(-)}}{2{\epsilon }_0}\right]$
$E=\frac{1}{2{\epsilon }_0}\left[{\sigma }_{(+)}-{\sigma }_{(-)}\right]=\frac{(6.8-4.3)\times 10^{-6}}{2\times 8.85\times 10^{-12}}$
$=1.41\times 10^{5}N/C$ towards right