Question 1

According to Gauss's law, what is the total electric flux $$\Phi_E$$ through a closed surface that encloses a net charge $$Q_{in}$$?

Accepted Answer

$$\Phi_E = Q_{in} / \$$varepsilon_0$$

Question 2

A long, straight wire carries a uniform linear charge density $$\lambda. $$Using Gauss's law and the concept of cylindrical symmetry, what is the magnitude of the electric field $$E at a $$distance $$r$$ from the wire?

Accepted Answer

$$E = \dfrac{\lambda}{2 \pi \$$varepsilon_0$$ r}$$

Question 3

Which of the following statements about conductors in electrostatic equilibrium is correct?

Accepted Answer

The electric field inside the conductor is zero.

Question 4

A spherical shell of radius $$R$$ carries a total charge $$Q$$ uniformly distributed on its surface. What is the electric field at a point inside the shell ($$r \u003c R$$)?

Accepted Answer

$$E = 0$$

Question 5

Which symmetry is most appropriate for applying Gauss’s law to find the electric field of an infinite plane of charge?

Accepted Answer

Planar symmetry

Question 6

A cube encloses a point charge $$q. If $$the electric field at every point on the surface of the cube is $$E$$, what is the total electric flux through the cube?

Accepted Answer

$$\Phi_E = q / \$$varepsilon_0$$

Question 7

A solid non-conducting sphere of radius $$R$$ has a uniform charge density $$\rho. $$What is the electric field at a distance $$r \u003c R$$ from the center?

Accepted Answer

$$E = \dfrac{\rho r}{3 \$$varepsilon_0$$}$$

Question 8

Which of the following best describes electric flux?

Accepted Answer

The amount of electric field passing through a surface

Question 9

A conducting sphere is placed in an external electric field. What happens to the electric field inside the sphere after electrostatic equilibrium is reached?

Accepted Answer

It becomes zero.

Question 10

A long, uniformly charged cylinder has a charge per unit length $$\lambda. $$What is the electric field outside the cylinder at a distance $$r$$ from its axis?

Accepted Answer

$$E = \dfrac{\lambda}{2 \pi \$$varepsilon_0$$ r}$$

Question 11

Which of the following is NOT a property of conductors in electrostatic equilibrium?

Accepted Answer

The electric field inside the conductor is nonzero.

Question 12

If a closed surface encloses no net charge, what is the total electric flux through the surface?

Accepted Answer

$$\Phi_E = 0$$

Question 13

A point charge $$q is $$placed at the center of a spherical Gaussian surface of radius $$R. $$What is the electric field at the surface?

Accepted Answer

$$E = \dfrac{q}{4 \pi \$$varepsilon_0$$ R^2$}$$

Question 14

Which of the following is a correct application of Gauss’s law?

Accepted Answer

Finding the electric field outside a uniformly charged sphere

Question 15

A non-conducting infinite plane has a uniform surface charge density $$\sigma. $$What is the electric field just above the surface?

Accepted Answer

$$E = \dfrac{\sigma}{2 \$$varepsilon_0$$}$$

Question 16

Which of the following best explains why Gauss’s law is easier to use than superposition for certain charge distributions?

Accepted Answer

It takes advantage of symmetry to simplify calculations.

Gauss's Law and Electric Flux: Symmetry and Applications

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