Part A:

A voltmeter reads 46.0 V when placed across the capacitor. When a dielectric is inserted between the plates, completely filling the space, the voltmeter reads 15.0 V. What is the dielectric constant of this material?

Part B:

What will the voltmeter read if the dielectric is now pulled partway out so it fills only one-third of the space between the plates?

I know how to do part A using K = Vo/V, But i do not know how to work the problem if it involve partial dielectric.Any helps or hints would be great thanks.