Exam 4: Energy and Capacitance

A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them.When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates.While it is connected to the battery the space between the plates is filled with a material of dielectric constant 3.After the dielectric is added, the magnitude of the charge on the plates and the potential difference between them are:

The plates of a parallel plate capacitor of capacitance are horizontal.Into the gap a slab of dielectric material with is placed, filling the bottom half of the gap between the plates.What is the resulting new capacitance?

A parallel plate capacitor is charged to voltage V and then disconnected from the battery.Leopold says that the voltage will decrease if the plates are pulled apart.Gerhardt says that the voltage will remain the same.Which one, if either, is correct, and why?

A 15- $\mu$ F capacitor and a 25- $\mu$ F capacitor are connected in parallel, and charged to a potential difference of 60 V.How much energy is then stored in this capacitor combination?

An initially uncharged parallel plate capacitor of capacitance C is charged to potential V by a battery.The battery is then disconnected.Which statement is correct?

A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them.When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates.It is then disconnected from the battery and the plates are pulled apart to a separation 2d without discharging them.After the plates are 2d apart, the new capacitance and the potential difference between the plates are

A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them.When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates.It is then disconnected from the battery and the plates are pulled apart to a separation 2d without discharging them.After the plates are 2d apart, the magnitude of the charge on the plates and the potential difference between them are:

Regarding the Earth and a cloud layer 800 m above the Earth as the 'plates' of a capacitor, calculate the capacitance if the cloud layer has an area of 1.0 km2.If an electric field of 2.0 * 106 N/C makes the air break down and conduct electricity (lightning), what is the maximum charge the cloud can hold?

A 30- $\mu$ F capacitor is charged to an unknown potential V0 and then connected across an initially uncharged 10- $\mu$ F capacitor.If the final potential difference across the 10- $\mu$ F capacitor is 20 V, determine V0.

A capacitor of unknown capacitance C is charged to 100 V and then connected across an initially uncharged 60- $\mu$ F capacitor.If the final potential difference across the 60- $\mu$ F capacitor is 40 V, determine C.

A 0.16 pF parallel-plate capacitor is charged to 10 V.Then the battery is disconnected from the capacitor.When 1.00 * 107 electrons are now placed on the negative plate of the capacitor, the voltage between the plates changes by:

A 6.0- $\mu$ F capacitor charged to 50 V and a 4.0- $\mu$ F capacitor charged to 34 V are connected to each other, with the two positive plates connected and the two negative plates connected.What is the total energy stored in the 6.0- $\mu$ F capacitor at equilibrium?

A 15- $\mu$ F capacitor and a 30- $\mu$ F capacitor are connected in series, and charged to a potential difference of 50 V.What is the resulting charge on the 30- $\mu$ F capacitor?

A 0.120 pF parallel-plate capacitor is charged to a potential difference of 10.0 V and then disconnected from the battery.A cosmic ray burst creates 1.00 * 106 electrons and 1.00 * 106 positive charges between the plates.If the charges do not recombine, but reach the oppositely charged plates, by how much is the potential difference between the capacitor plates reduced?

A 30- $\mu$ F capacitor is charged to 80 V and then connected across an initially uncharged capacitor of unknown capacitance C.If the final potential difference across the 30- $\mu$ F capacitor is 20 V, determine C.

A parallel plate capacitor is connected to a battery and charged to voltage V.Leah says that the charge on the plates will decrease if the distance between the plates is increased while they are still connected to the battery.Gertie says that the charge will remain the same.Which one, if either, is correct, and why?

Which of the following is not a capacitance?

Two spheres are made of conducting material.Sphere #2 has twice the radius of Sphere #1.What is the ratio of the capacitance of Sphere #2 to the capacitance of sphere #1?

A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them.When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates.It is then disconnected from the battery and the space between the plates is filled with a material of dielectric constant 3.After the dielectric is added, the magnitudes of the capacitance and the potential difference between the plates are:

Is it feasible to construct an air-filled parallel-plate capacitor that has its two plates separated by 0.10 mm and has a capacitance of 1.0 F? Why or why not?