Physics

Problem

A parallel-plate capacitor with air between its plates is charged to a potential difference of

600\,\text{V}

and then disconnected from the battery so that the free charge on the plates remains constant. The plate separation is

3\,\text{mm}

. A

3\,\text{mm}

-thick plastic slab of dielectric constant

\kappa = 5.0

is then inserted fully between the plates, completely filling the space. What is the new potential difference between the plates? a)

600\,\text{V}

120\,\text{V}

3.0\times10^{3}\,\text{V}

1.2\times10^{3}\,\text{V}