College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 40

When a certain air-filled parallel-plate capacitor is connected across a battery, it acquires a charge of 150 C on each plate. While the battery connection is maintained, a dielectric slab is inserted into, and fills, the region between the plates. This results in the accumulation of an additional charge of 200 C on each plate. What is the dielectric constant of the slab