Question 1

Which of the following best describes the relationship between electric potential energy and the work done by the electric force when moving a charge in an electric field?

Accepted Answer

The change in electric potential energy is the negative of the work done by the electric force.

Question 2

What is the SI unit of electric potential, and how is it defined?

Accepted Answer

The volt (V), defined as one joule per coulomb: $$1\ \mathrm{V} = 1\ \mathrm{J}/\mathrm{C}$$

Question 3

A positive charge is released from rest in a region of decreasing electric potential. What happens to its kinetic and potential energy?

Accepted Answer

Its kinetic energy increases and its electric potential energy decreases.

Question 4

Which equation correctly gives the electric potential $$V at a $$distance $$r$$ from a point charge $$q$$?

Accepted Answer

$$V = \dfrac{kq}{r}$$

Question 5

How is the electric field $$\vec{E}$$ related to the electric potential $$V$$?

Accepted Answer

$$\vec{E} = -
abla V$$

Question 6

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

The electric field is always perpendicular to equipotential surfaces.

Question 7

A parallel-plate capacitor has plates of area $$A$$ separated by distance $$d. $$What is the expression for its capacitance $$C in $$vacuum?

Accepted Answer

$$C = \$$varepsilon_0$$ \dfrac{A}{d}$$

Question 8

What effect does inserting a dielectric with dielectric constant $$\kappa$$ between the plates of a capacitor have on its capacitance?

Accepted Answer

The capacitance increases by a factor of $$\kappa.$$

Question 9

Which of the following best describes dielectric breakdown?

Accepted Answer

It occurs when the electric field in a dielectric becomes large enough to tear electrons from atoms, making the material conductive.

Question 10

A capacitor is charged to a potential difference $$V$$ and stores a charge $$Q. $$What is the energy $$U$$ stored in the capacitor?

Accepted Answer

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

Question 11

Which of the following real-world devices relies on the rapid discharge of a capacitor for its operation?

Accepted Answer

A camera flash

Question 12

If the energy density $$u in an $$electric field is given by $$u = \dfrac{1}{2}\$$varepsilon_0$$ E^2$, what does this represent?

Accepted Answer

The energy stored per unit volume in the electric field

Question 13

A negative charge is released from rest in a region of increasing electric potential. What happens to its motion?

Accepted Answer

It accelerates in the direction of increasing potential.

Question 14

Which of the following statements about conductors and equipotential surfaces is correct?

Accepted Answer

An ideal conductor is an equipotential surface.

Question 15

The electric potential energy $$U of $$two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r is $$given by:

Accepted Answer

$$U = \dfrac{k q_1$ q_2$}{r}$$

Question 16

Which of the following best explains why the electric field is strongest where equipotential lines are closest together?

Accepted Answer

A greater change in potential occurs over a smaller distance, indicating a stronger field.

Question 17

A parallel-plate capacitor is filled with a dielectric material of dielectric constant $$\kappa. $$What is the new capacitance $$C'$$ compared to the original capacitance $$C_0$$?

Accepted Answer

$$C' = \kappa C_0$

Question 18

Which of the following medical devices uses the concept of electric potential differences to monitor electrical activity in the human body?

Accepted Answer

Electrocardiograph (ECG)

Question 19

If a capacitor with capacitance $$C is $$connected to a battery of voltage $$V$$, and the dielectric is removed while the battery remains connected, what happens to the stored energy?

Accepted Answer

The stored energy decreases.

Question 20

Which of the following is a correct statement about the total electric potential due to a group of point charges?

Accepted Answer

It is the algebraic sum of the potentials due to each charge.

Electric Potential and Electric Potential Energy: Study Notes

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