Q: A disk of radius $$0.200 m is $$placed in a uniform electric field of $$E = 40.0 N/C. $$The disk is oriented perpendicular to the field. What is the electric flux through the disk?

$$\Phi = 40.0 \times \pi \times (0.200)^2$

Q: A hollow conducting sphere of radius $$0.250 m $$has an inward electric field of $$180 N/C at a $$distance $$0.300 m $$from its center. What is the net charge on the sphere?

$$Q = -4\pi \$$epsilon_0$$ (0.300)^2$ \times 180$$

Question 1

Which of the following statements best describes electric flux through a closed surface according to Gauss's Law?

Accepted Answer

Electric flux through a closed surface is directly proportional to the net charge enclosed within the surface and independent of the surface's size.

Question 2

A cube is placed in a uniform electric field such that the field is parallel to one of its faces. What is the net electric flux through the cube?

Accepted Answer

$$\Phi = 0$$

Question 3

A point charge $$q is $$placed at the center of an imaginary sphere of radius $$r. $$What is the electric flux through the sphere?

Accepted Answer

$$\Phi = \dfrac{q}{\$$epsilon_0$$}$$

Question 4

Which Gaussian surface would you choose to find the electric field due to an infinitely long, straight, charged wire?

Accepted Answer

A coaxial cylindrical surface

Question 5

A conducting sphere of radius $$R$$ carries a total charge $$Q on $$its surface. What is the electric field just outside the surface?

Accepted Answer

$$E = \dfrac{Q}{4\pi \$$epsilon_0$$ R^2$}$$

Question 6

A thin, infinite sheet has a uniform surface charge density $$\sigma. $$What is the magnitude of the electric field just above the sheet?

Accepted Answer

$$E = \dfrac{\sigma}{2\$$epsilon_0$$}$$

Question 7

A solid insulating sphere of radius $$R$$ has a total charge $$Q$$ uniformly distributed throughout its volume. What is the electric field at a distance $$r$$ from the center, where $$r \u003c R$$?

Accepted Answer

$$E = \dfrac{Q r}{4\pi \$$epsilon_0$$ R^3$}$$

Question 8

A solid conductor contains a cavity with a point charge $$q$$ inside the cavity. The conductor itself carries a net charge $$Q. $$What is the total charge on the inner surface of the cavity?

Accepted Answer

$$-q$$

Question 9

A disk of radius $$0.200 m is $$placed in a uniform electric field of $$E = 40.0 N/C. $$The disk is oriented perpendicular to the field. What is the electric flux through the disk?

Accepted Answer

$$\Phi = 40.0 	imes \pi 	imes (0.200)^2$

Question 10

Which of the following is a correct mathematical statement of Gauss's Law?

Accepted Answer

$$\oint \vec{E} \cdot d\vec{A} = \dfrac{Q_{enc}}{\$$epsilon_0$$}$$

Question 11

A hollow conducting sphere of radius $$0.250 m $$has an inward electric field of $$180 N/C at a $$distance $$0.300 m $$from its center. What is the net charge on the sphere?

Accepted Answer

$$Q = -4\pi \$$epsilon_0$$ (0.300)^2$ 	imes 180$$

Question 12

A solid conductor with a cavity carries a total charge of $$+7.00 nC. $$Inside the cavity, a point charge of $$+5.00 nC is $$placed. What is the charge on the outer surface of the conductor?

Accepted Answer

$$+7.00 nC$$

Question 13

Which of the following is true about the location of excess charge on a solid conductor at rest?

Accepted Answer

Excess charge resides entirely on the surface.

Question 14

A cylindrical Gaussian surface of length $$L$$ and radius $$r$$ surrounds a long straight wire with linear charge density $$\lambda. $$What is the electric field at distance $$r$$ from the wire?

Accepted Answer

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

Question 15

If a closed surface encloses both a $$+q$$ and a $$-q$$ charge, what is the net electric flux through the surface?

Accepted Answer

$$\Phi = 0$$

Question 16

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

Accepted Answer

$$\Phi = EA \cos 	heta$$

Question 17

Which of the following is NOT a valid use of a Gaussian surface?

Accepted Answer

To measure the electric field at a point outside the surface without symmetry

Question 18

A solid insulating sphere of radius $$R$$ has a total charge $$Q$$ uniformly distributed throughout its volume. What is the electric field at the surface ($$r = R$$)?

Accepted Answer

$$E = \dfrac{Q}{4\pi \$$epsilon_0$$ R^2$}$$

Question 19

A closed surface encloses no net charge, but is placed in a region with a uniform electric field. What is the net electric flux through the surface?

Accepted Answer

$$\Phi = 0$$

Chapter 22- Gauss's Law and Electric Flux (Exam 2, Physics 1320)

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