Question

A parallel plate capacitor with plate separation d is connected to a battery. The capacitor is fully charged to Q Coulombs and a voltage of V. (C is the capacitance and U is the stored energy.) Answer the following questions regarding the capacitor charged by a battery. For each statement below, select True or False.

True or False With the capacitor connected to the battery, increasing d decreases Q.
True or False  After being disconnected from the battery, inserting a dielectric with κ will increase U.
True or False  After being disconnected from the battery, inserting a dielectric with κ will decrease C.
True or False With the capacitor connected to the battery, increasing d increases U.
True or False  With the capacitor connected to the battery, increasing d increases C.
True or False  After being disconnected from the battery, inserting a dielectric with κ will decrease V.

Answer 1

Solution:

1. True

Charge Q

As battery is connected, potential difference V will remain constant

The capacitance C

If the distance d between plates is increases, then capacitance C will decrease.

Hence, Charge Q will also decrease.

2. False

The capacitor is disconnected, hence, charge Q is constant.

Energy stored inside capacitor is U

The capacitance C

On inserting dielectric, the dielectric constant value is more than 1, thus, capacitance C will increase.

Hence, the stored energy inside capacitor will decrease.

3. False

The capacitor is disconnected, hence, charge Q is constant.

The capacitance C

On inserting dielectric, the dielectric constant value is more than 1, thus, capacitance C will increase.

4. False

The battery is connected, potential difference V will remain constant.

The energy stored in capacitor is U

The capacitance C

If the distance d between plates is increases, then capacitance C will decrease.

Hence, the energy stored in the capacitor U will also decrease.

5. False

The battery is connected, potential difference V will remain constant.

The capacitance C

If the distance d between plates is increases, then capacitance C will decrease.

6. True

The capacitor is disconneccted, hence, charge Q is constant.

Charge Q

The capacitance C

On inserting dielectric, the dielectric constant value is more than 1, thus, capacitance C will increase.

Hence, the potential difference on capacitor plates will decrease.