Question 1

Which of the following best describes the relationship between electric potential (V) and electric potential energy (U) for a test charge $$q_0$$?

Accepted Answer

$$V = U/q_0$

Question 2

A point charge $$q is $$located at the origin. What is the electric potential $$V at a $$distance $$r$$ from the charge?

Accepted Answer

$$V = kq/r$$

Question 3

Refer to the third image (dipole configuration). At the midpoint between the two charges, what is the electric potential?

Accepted Answer

$$V = 0$$

Question 4

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

The electric field is always perpendicular to equipotential surfaces.

Question 5

Given two point charges $$q_1 = 2$$\ \mathrm{nC}$$ at r_1$ = 5\ \mathrm{cm}$$ and $$q_2 = 4$$\ \mathrm{nC}$$ at r_2$ = 2\ \mathrm{cm}$$ from point P, what is the total electric potential at P?

Accepted Answer

$$V_P = k\left(\frac{q_1$}{r_1$} + \frac{q_2$}{r_2$}\right)$$

Question 6

A proton is released from rest at a point where the electric potential is $$120\ \mathrm{V}$$ higher than at another point. What is the change in its kinetic energy as it moves to the lower potential?

Accepted Answer

$$\Delta K = e \cdot 120\ \mathrm{V}$$

Question 7

Which of the following is true for points A and B on the same equipotential surface?

Accepted Answer

$$V_A = V_B$$

Question 8

If the electric field $$\vec{E} is $$zero along a path from point A to point B, what is the potential difference $$V_A - V_B$$?

Accepted Answer

$$V_A - V_B = 0$$

Question 9

For a uniform line of charge with linear charge density $$\lambda$$, what is the electric potential at a distance $$r$$ from the line?

Accepted Answer

$$V = \frac{\lambda}{2\pi\$$epsilon_0$$} \ln\left(\frac{r}{r_0$}\right)$$

Question 10

Which mathematical operation relates the electric field $$\vec{E} to $$the electric potential $$V$$?

Accepted Answer

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

Question 11

A test charge $$q_0 is $$placed at a point where the electric potential is $$V. $$What is the potential energy of the test charge?

Accepted Answer

$$U = q_0$ V$$

Question 12

Which of the following is a property of a conservative electric field?

Accepted Answer

The work done moving a charge between two points is independent of the path taken.

Question 13

In the fourth image (two equal positive charges), what is the value of the electric potential at the midpoint between the charges?

Accepted Answer

$$V = +70\ \mathrm{V}$$

Question 14

A charge $$q$$ moves from point A to point B in an electric field. The potential at A is $$V_A$$ and at B is $$V_B. $$What is the work done by the electric field?

Accepted Answer

$$W = q(V_A - V_B)$$

Question 15

Which of the following best describes the unit of electric potential?

Accepted Answer

Volt, which is equivalent to $$1\ \mathrm{J}/1\ \mathrm{C}$$

Question 16

If the electric potential at a point due to three charges is $$V = k\left(\frac{q_1$}{r_1$} + \frac{q_2$}{r_2$} + \frac{q_3$}{r_3$}\right)$$, what is the potential energy of a test charge $$q_0$$ placed at that point?

Accepted Answer

$$U = q_0$ V$$

Question 17

A thin rod of length $$L$$ has a uniform charge density $$\lambda. $$What is the electric potential at a distance $$a$$ from one end along the axis of the rod?

Accepted Answer

$$V = k\lambda \ln\left(1 + \frac{L}{a}\right)$$

Question 18

Which of the following is true about the direction of electric field lines relative to equipotential surfaces?

Accepted Answer

Electric field lines are always perpendicular to equipotential surfaces.

Question 19

If $$\vec{E} = -
abla V$$, what is the $$x-$$component of the electric field in terms of the potential $$V(x, y, z)$$?

Accepted Answer

$$E_x = -\frac{\partial V}{\partial x}$$

Electric Potential and Potential Energy: Concepts, Calculations, and Applications

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