Question 1

A uniform electric field $$\vec{E}$$ passes through a flat surface of area $$A at an $$angle $$	heta to $$the normal. What is the electric flux $$\Phi_E$$ through the surface?

Accepted Answer

$$\Phi_E = EA \cos 	heta$$

Question 2

A spherical Gaussian surface of radius $$r$$ encloses a point charge $$q. $$What is the electric flux through the surface?

Accepted Answer

$$\Phi_E = q/\$$epsilon_0$$

Question 3

Which of the following statements about Gauss's Law is correct?

Accepted Answer

Gauss's Law relates the electric flux through a closed surface to the total charge enclosed.

Question 4

A long, straight 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

$$E = \lambda/(2\pi\$$epsilon_0$$ r)$$

Question 5

A hollow conducting sphere of radius $$R$$ has a charge $$Q$$ placed on its surface. What is the electric field inside the sphere ($$r \u003c R$$)?

Accepted Answer

$$E = 0$$

Question 6

How much work is required to assemble two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r$$?

Accepted Answer

$$W = q_1$ q_2$/(4\pi\$$epsilon_0$$ r)$$

Question 7

A parallel plate capacitor is being assembled by moving a charge $$Q$$ from one plate to the other. If the potential difference between the plates is $$V$$, what is the work done by the external force?

Accepted Answer

$$W = QV$$

Question 8

Which of the following best describes electric potential at a point?

Accepted Answer

The work required to move a unit charge from infinity to that point.

Question 9

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

Accepted Answer

$$V = q/(4\pi\$$epsilon_0$$ r)$$

Question 10

A 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

$$E = \rho r/(3\$$epsilon_0$$)$$

Question 11

A thin spherical shell of radius $$R$$ carries a uniform charge $$Q. $$What is the electric potential at the center of the shell?

Accepted Answer

$$V = Q/(4\pi\$$epsilon_0$$ R)$$

Question 12

A charged particle 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 change in potential energy of the particle of charge $$q$$?

Accepted Answer

$$\Delta U = q(V_B - V_A)$$

Question 13

A conducting shell encloses a charge $$q at $$its center. What is the electric field just outside the shell?

Accepted Answer

$$E = q/(4\pi\$$epsilon_0$$ R^2$)$$

Question 14

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

Accepted Answer

$$E = \sigma/(2\$$epsilon_0$$)$$

Question 15

A charge $$q is $$distributed uniformly along a ring of radius $$R. $$What is the electric potential at the center of the ring?

Accepted Answer

$$V = q/(4\pi\$$epsilon_0$$ R)$$

Question 16

A charged particle is released from rest in a uniform electric field. Which statement is true about its motion?

Accepted Answer

It accelerates in the direction of the electric field if its charge is positive.

Question 17

A cube of side $$a is $$placed in a uniform electric field $$\vec{E}$$ parallel to one of its faces. What is the net electric flux through the cube?

Accepted Answer

$$\Phi_E = 0$$

Question 18

A point charge $$q is $$placed at the center of a cube. What is the electric flux through one face of the cube?

Accepted Answer

$$\Phi_E = q/(6\$$epsilon_0$$)$$

Electric Flux, Gauss's Law, Work to Assemble, and Electric Potential: Study Guide

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