Question 1

Which of the following statements best describes the electric field produced by a uniformly charged infinite plane sheet with surface charge density $$\sigma$$?

Accepted Answer

The field is constant in magnitude and direction on both sides of the sheet.

Question 2

A thin ring of radius $$R$$ carries a total charge $$Q$$ distributed uniformly. What is the expression for the electric field at a point $$z$$ along the axis perpendicular to the plane of the ring?

Accepted Answer

$$E = \frac{kQz}{(z^2$ + R^2$)^{3/2}$$}$

Question 3

Which of the following is a correct application of Gauss’s Law for a point charge $$q$$ located at the center of a spherical Gaussian surface of radius $$R$$?

Accepted Answer

$$\Phi_E = \frac{q}{\$$epsilon_0$$}$$

Question 4

A solid conductor contains a hollow cavity with no charge inside. What is the electric field inside the cavity?

Accepted Answer

Zero everywhere inside the cavity.

Question 5

If a charge $$q is $$placed inside a cavity within a conductor, what happens to the charge distribution on the conductor?

Accepted Answer

A charge $$-q$$ appears on the cavity surface and $$+q on $$the outer surface.

Question 6

Which of the following best describes the net electric flux through a closed surface that encloses no net charge?

Accepted Answer

The net electric flux is zero.

Question 7

An infinitely long wire carries a uniform linear charge density $$\lambda. $$Using Gauss’s Law, what is the magnitude of the electric field at a distance $$r$$ from the wire?

Accepted Answer

$$E = \frac{\lambda}{2\pi\$$epsilon_0$$ r}$$

Question 8

A child stands inside a large, charged metal shell. What happens to the electric field inside the shell?

Accepted Answer

The electric field is zero everywhere inside the shell.

Question 9

Which of the following is the correct expression for the electric flux $$\Phi_E$$ through a flat surface of area $$A$$ perpendicular to a uniform electric field $$E$$?

Accepted Answer

$$\Phi_E = EA$$

Question 10

A non-uniform electric field passes through a surface. How is the total electric flux through the surface calculated?

Accepted Answer

$$\Phi_E = \int \vec{E} \cdot d\vec{A}$$

Question 11

For a spherical Gaussian surface of radius $$R$$ enclosing a point charge $$q$$, what happens to the electric flux if the radius is doubled?

Accepted Answer

The flux remains the same.

Question 12

A conducting box is placed in a uniform external electric field. What is the electric field inside the box?

Accepted Answer

Zero everywhere inside the box.

Question 13

Which of the following is true about the electric field inside a conductor in electrostatic equilibrium?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 14

A Gaussian surface encloses two positive charges and one negative charge. What is the net electric flux through the surface?

Accepted Answer

$$\Phi_E = \frac{q_1$ + q_2$ - q_3$}{\$$epsilon_0$$}$$

Question 15

Which of the following is a consequence of Gauss’s Law for a conductor in electrostatic equilibrium?

Accepted Answer

Any excess charge resides entirely on the surface of the conductor.

Question 16

A flat surface of area $$A is $$placed at an angle $$	heta to a $$uniform electric field $$E. $$What is the electric flux through the surface?

Accepted Answer

$$\Phi_E = EA \cos 	heta$$

Question 17

Which of the following is true about the electric field at the center of a uniformly charged ring?

Accepted Answer

The electric field is zero.

Question 18

For a charged ring, what happens to the electric field along the axis as the distance $$z$$ from the center becomes much larger than the radius $$R$$?

Accepted Answer

The field approaches that of a point charge: $$E = \frac{kQ}{z^2$}.$$

Question 19

A Gaussian surface is constructed inside a conductor. What must be true about the net charge enclosed by this surface?

Accepted Answer

The net charge enclosed must be zero.

Fields of Continuous Charge Distributions and Gauss’s Law

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