Question 1

A positive charge $$q is $$released from rest in a uniform electric field $$E$$ between two parallel plates separated by distance $$d. $$What is the change in electric potential energy as the charge moves from the positive plate to the negative plate?

Accepted Answer

$$\Delta U_{elec} = -qEd$$

Question 2

Which of the following statements about the electric potential $$V is $$correct?

Accepted Answer

The electric potential at a point depends only on the source charges, not on the test charge.

Question 3

A proton is released from rest at a point of high electric potential. What happens to its kinetic and potential energy as it moves?

Accepted Answer

Its electric potential energy decreases and its kinetic energy increases.

Question 4

The electric potential energy of two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r is $$given by which formula?

Accepted Answer

$$U_{elec} = \frac{K q_1$ q_2$}{r}$$

Question 5

A negative charge moves in the direction of the electric field in a parallel-plate capacitor. What happens to its potential energy and speed?

Accepted Answer

Its potential energy increases and its speed decreases.

Question 6

Which of the following is true about the work done by the electric force when moving a charge between two points?

Accepted Answer

It depends only on the initial and final positions, not the path taken.

Question 7

If the electric potential at point A is 9 V and at point B is 3 V, what is the ratio $$V_B/V_A$$?

Accepted Answer

$$1/3$$

Question 8

A positive and a negative charge are released from rest in vacuum and move toward each other. What happens to the electric potential energy of the system?

Accepted Answer

A negative potential energy becomes less negative.

Question 9

The electric potential inside a parallel-plate capacitor is given by $$V = Es. $$What does $$s$$ represent?

Accepted Answer

The distance from the negative electrode.

Question 10

Which of the following units are equivalent for electric field strength?

Accepted Answer

$$1\ \mathrm{N/C} = 1\ \mathrm{V/m}$$

Question 11

A positive charge is released from rest. In which direction does it move?

Accepted Answer

Toward lower electric potential.

Question 12

The electric potential at a distance $$r$$ from a point charge $$q is $$given by:

Accepted Answer

$$V = \frac{1}{4\pi\$$epsilon_0$$} \frac{q}{r}$$

Question 13

A system consists of three point charges $$q_1$$, $$q_2$$, and $$q_3 at $$distances $$r_{12}$$, $$r_{13}$$, and $$r_{23}$$ from each other. What is the total electric potential energy of the system?

Accepted Answer

$$U_{elec} = K \left( \frac{q_1$ q_2$}{r_{12}} + \frac{q_1$ q_3$}{r_{13}} + \frac{q_2$ q_3$}{r_{23}} \right)$$

Question 14

A proton is launched with speed $$v$$ from point 1 inside a parallel-plate capacitor and follows two different trajectories to points 2 and 3. If the electric potential at point 2 is lower than at point 3, which statement is correct about the speeds $$v_2$$ and $$v_3 at $$these points?

Accepted Answer

$$v_2$$ \u003e $$v_3$$

Question 15

At the midpoint between two equal but opposite charges, what are the values of the electric field $$\vec{E}$$ and the electric potential $$V$$?

Accepted Answer

$$\vec{E} = 0;\ V = 0$$

Question 16

A battery is rated at 1.5 V. What does this voltage represent?

Accepted Answer

The electric potential difference between the positive and negative terminals.

Question 17

Which of the following best describes the relationship between electric field lines and equipotential surfaces inside a parallel-plate capacitor?

Accepted Answer

Electric field lines are perpendicular to equipotential surfaces.

Question 18

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

Accepted Answer

It speeds up.

Question 19

Which equation expresses the conservation of energy for a charged particle moving through a changing electric potential?

Accepted Answer

$$K_f + qV_f = K_i + qV_i$$

Chapter 25: The Electric Potential – Structured Study Notes

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