Question

A parallel plate capacitor has two square plates with equal and opposite charges. The surface charge densities on the plate are $+\sigma$ and $-\sigma$ respectively. In the region between the plates the magnitude of electric field is:

• A. $\frac{\sigma }{2{\epsilon }_0}$
• B. $\frac{\sigma }{{\epsilon }_0}$
• C. 0
• D. none of these

Answer 1

The correct option is B $\frac{\sigma }{{\epsilon }_0}$

The magnitude of the electric field due to a charged plate is given as:

$\overrightarrow{E}=\frac{\sigma }{2{\epsilon }_0}$

The charge density on the upper plate is positive whereas on the lower plate it is negative.

Therefore, the electric field in the region between the two plates is the difference of the two fields.

It is given as:

$E_{net}=\frac{\sigma }{2{\epsilon }_0}-\frac{-\sigma }{2{\epsilon }_0}$

$E_{net}=\frac{\sigma }{{\epsilon }_0}$