Question

Two very thin circular plastic sheets are close to each other and carry equal and opposite uniform charge. Explain briefly why the field between the sheets is much larger than the field outside. Illustrate your argument on a diagram.

Short answer

The field is much larger between the sheets because the two individual fields add up here. The diagram is drawn below.

Step-by-step solution

Given data

A rod with uniformly distributed positive charge

Electric field direction

Electric field is directed away from a positive charge distribution and is directed toward a negative charge distribution

Determination of the field between the sheets and outside

The direction of the field from the positive sheet $\left(E_{+}\right)$ and the negative sheet $\left(E_{-}\right)$ in between the sheets and outside are depicted in the following figure:

As can be seen from the figure, the two fields are parallel in between the sheets and anti-parallel outside. Thus in between the sheets they add up, whereas they get subtracted outside. Hence the magnitude of field is maximum in between the sheets.