Question 1

A parallel-plate capacitor has plates of area $$A$$ separated by a distance $$d. If $$the charge on the plates is $$Q$$ and the potential difference between the plates is $$V$$, what is the correct expression for the capacitance $$C of $$the capacitor?

Accepted Answer

$$C = \dfrac{Q}{V}$$

Question 2

Which of the following changes will increase the capacitance of a parallel-plate capacitor the most, assuming all other factors remain constant?

Accepted Answer

All of the above

Question 3

Two capacitors, $$C_1 = 4$$\,\mu\mathrm{F}$$ and C_2$ = 6\,\mu\mathrm{F}$$, are connected in series. What is the equivalent capacitance $$C_{eq}$$?

Accepted Answer

$$C_{eq} = 2.4\,\mu\mathrm{F}$$

Question 4

A $$10\,\mu\mathrm{F}$$ and a $$20\,\mu\mathrm{F}$$ capacitor are connected in parallel across a $$100\,\mathrm{V}$$ battery. What is the total charge stored in the system?

Accepted Answer

$$Q = 3000\,\mu\mathrm{C}$$

Question 5

The energy stored in a capacitor is given by which of the following expressions?

Accepted Answer

$$U = \dfrac{1}{2}CV^2$

Question 6

A $$6.00\,\mu\mathrm{F}$$ capacitor is charged to $$100\,\mathrm{V}$$ and then disconnected from the battery. If a $$3.00\,\mu\mathrm{F}$$ uncharged capacitor is then connected in parallel to it, what is the final voltage across both capacitors?

Accepted Answer

$$66.7\,\mathrm{V}$$

Question 7

A parallel-plate capacitor is filled with a dielectric material of dielectric constant $$K. $$Which of the following statements is correct?

Accepted Answer

The capacitance increases by a factor of $$K$$

Question 8

If the area of the plates of a parallel-plate capacitor is doubled and the distance between them is halved, by what factor does the capacitance change?

Accepted Answer

It becomes four times larger

Question 9

A $$360\,\mathrm{nF}$$ air capacitor is connected to a power supply and stores $$1.85 	imes 10$$^{-5}$$\,\mathrm{J} of $$energy. If a dielectric is inserted and the stored energy increases by $$2.32 	imes 10$$^{-5}$$\,\mathrm{J} ($$with the voltage constant), what is the dielectric constant $$K of $$the slab?

Accepted Answer

$$K = 2.25$$

Question 10

Which of the following best describes the effect of inserting a dielectric into a charged capacitor that is disconnected from a battery?

Accepted Answer

The voltage across the plates decreases

Question 11

A $$12\,\mu\mathrm{F}$$ and a $$6\,\mu\mathrm{F}$$ capacitor are connected in series. What is the equivalent capacitance?

Accepted Answer

$$C_{eq} = 4\,\mu\mathrm{F}$$

Question 12

Which of the following is NOT a way to increase the capacitance of a parallel-plate capacitor?

Accepted Answer

Increase the potential difference across the plates

Question 13

A $$8.0\,\mu\mathrm{F}$$ capacitor is charged to $$120\,\mathrm{V}$$ and then disconnected from the battery. It is then connected in parallel with a $$4.0\,\mu\mathrm{F}$$ uncharged capacitor. What is the final energy stored in the system?

Accepted Answer

$$0.096\,\mathrm{J}$$

Question 14

Which of the following best describes polarization in a dielectric material?

Accepted Answer

Redistribution of positive and negative charge within a non-conducting material

Question 15

A capacitor is connected to a battery and fully charged. If the battery remains connected and a dielectric is inserted, what happens to the charge on the capacitor?

Accepted Answer

It increases

Question 16

Which of the following equations correctly relates the electric field $$E$$ between the plates of a parallel-plate capacitor with a dielectric to the surface charge density $$\sigma$$?

Accepted Answer

$$E = \dfrac{\sigma}{K\$$varepsilon_0$$}$$

Question 17

A capacitor is partially filled with a dielectric slab. Which of the following statements is true?

Accepted Answer

The capacitance is greater than with air alone but less than with the dielectric completely filling the space

Question 18

Which of the following best describes the energy stored in a capacitor as shown by the area under the $$Q vs$$ $$V$$ graph?

Accepted Answer

The area under the line is $$U = \dfrac{1}{2}QV$$

Question 19

In a series connection of capacitors, which of the following is always true?

Accepted Answer

The charge on each capacitor is the same

Capacitance and Dielectrics: Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards