Q: Which of the following is a correct statement about the potential of a dipole at a point far from the dipole ($$r \gg l$$)?

$$V = \frac{1}{4\pi\$$epsilon_0$$} \frac{p \cos \theta}{r^2$}$$

Question 1

Which of the following best describes the relationship between electric potential energy and electric potential for a point charge $$q at a $$point with potential $$V$$?

Accepted Answer

$$U = qV$$

Question 2

A positive test charge is moved from point $$a to $$point $$b in a $$uniform electric field $$\vec{E}$$, where $$b is at a $$lower potential than $$a. $$What happens to the electric potential energy of the charge?

Accepted Answer

It decreases and is converted into kinetic energy.

Question 3

Which equation correctly gives the potential difference $$V_{ba}$$ between two points $$a$$ and $$b$$ separated by distance $$d in a $$uniform electric field $$E$$?

Accepted Answer

$$V_{ba} = -Ed$$

Question 4

For a point charge $$Q$$, what is the electric potential $$V at a $$distance $$r$$ from the charge, assuming $$V=0 at $$infinity?

Accepted Answer

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

Question 5

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

The electric field is always perpendicular to equipotential surfaces.

Question 6

A lightning rod protects a building by:

Accepted Answer

Providing a path of low resistance for electric charge to flow safely to the ground.

Question 7

If two spherical conductors of radii $$r_1$$ and $$r_2$$ are connected by a conducting wire and are at the same potential, what is the ratio of their surface charge densities $$\$$sigma_1$$/\$$sigma_2$$?

Accepted Answer

$$\frac{\$$sigma_1$$}{\$$sigma_2$$} = \frac{r_2$}{r_1$}$$

Question 8

Which of the following is true for the electric potential due to a continuous charge distribution?

Accepted Answer

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

Question 9

A negative charge is released from rest in a region of uniform electric field. Which of the following statements is correct?

Accepted Answer

It moves from low potential to high potential.

Question 10

The potential energy change $$\Delta U$$ for a mass $$m in a $$gravitational field over height $$h is $$analogous to which expression for a charge $$q in an $$electric field over distance $$d$$?

Accepted Answer

$$\Delta U = qEd$$

Question 11

Which of the following best describes the relationship between the electric field $$\vec{E}$$ and the electric potential $$V in $$three dimensions?

Accepted Answer

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

Question 12

A ring of radius $$R$$ carries a total charge $$Q$$ distributed uniformly. What is the electric potential at a point $$P on $$the axis of the ring, a distance $$x$$ from the center?

Accepted Answer

$$V = \frac{1}{4\pi\$$epsilon_0$$} \frac{Q}{\sqrt{x^2$ + R^2$}}$$

Question 13

Which of the following is a correct statement about the potential of a dipole at a point far from the dipole ($$r \gg l$$)?

Accepted Answer

$$V = \frac{1}{4\pi\$$epsilon_0$$} \frac{p \cos 	heta}{r^2$}$$

Question 14

A household outlet typically provides a potential difference of:

Accepted Answer

$$10^2 V$$

Question 15

If a positive charge is moved along an equipotential surface, what is the work done by the electric field?

Accepted Answer

Zero

Question 16

Which of the following best explains why the hair of a child stands up when touching a Van de Graaff generator?

Accepted Answer

The hair becomes charged and repels other hairs due to like charges.

Question 17

A positive charge $$q is $$moved from point $$a to $$point $$b in $$the direction of a uniform electric field $$\vec{E}. $$What is the sign of the potential difference $$V_b - V_a$$?

Accepted Answer

Negative

Question 18

Which of the following is true about the potential at infinity for a point charge?

Accepted Answer

It is chosen to be zero as a reference.

Question 19

If the electric field in a region is zero, what can be said about the electric potential in that region?

Accepted Answer

The electric potential is constant.

Electric Potential and Potential Energy

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