Question 1

Which of the following best describes electric flux?

Accepted Answer

The number of electric field lines crossing a given area kept normal to the electric field lines.

Question 2

What is the SI unit of electric flux?

Accepted Answer

$$\mathrm{N \cdot m^2$ / C}$$

Question 3

A flat surface of area $$A is $$placed perpendicular to a uniform electric field $$E. $$What is the electric flux $$\Phi_E$$ through the surface?

Accepted Answer

$$\Phi_E = E \cdot A$$

Question 4

If the area $$A is $$tilted at an angle $$\phi$$ with respect to the electric field $$E$$, what is the formula for the electric flux?

Accepted Answer

$$\Phi_E = E \cdot A \cdot \cos(\phi)$$

Question 5

Which statement about the net electric flux through a closed surface is correct?

Accepted Answer

It is directly proportional to the net charge enclosed within the surface.

Question 6

A box contains a positive point charge $$+q. $$What is the direction of the net electric flux through the surface of the box?

Accepted Answer

Outward

Question 7

A box contains a negative point charge $$-q. $$What is the direction of the net electric flux through the surface of the box?

Accepted Answer

Inward

Question 8

If there is zero net charge inside a box, but an electric field is present, what is the net electric flux through the box?

Accepted Answer

It is zero.

Question 9

Which of the following scenarios will result in zero net electric flux through a closed surface?

Accepted Answer

Equal amounts of positive and negative charge are inside the surface.

Question 10

A flat surface of area $$0.5\ \mathrm{m^2$} is $$placed in a uniform electric field of $$200\ \mathrm{N/C} at an $$angle of $$30^\circ to $$the field. What is the electric flux through the surface?

Accepted Answer

$$\Phi_E = 200 \cdot 0.5 \cdot \cos(30^\circ) = 86.6\ \mathrm{N \cdot m^2$ / C}$$

Question 11

Which of the following is true about the net electric flux through a closed surface if a charge is located near, but not inside, the surface?

Accepted Answer

The net electric flux is zero.

Question 12

For a nonuniform electric field, how is the total electric flux through a surface calculated?

Accepted Answer

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

Question 13

A student claims that doubling the size of a closed surface around a point charge will double the net electric flux. Is this correct?

Accepted Answer

No, because flux depends only on the enclosed charge.

Question 14

Which of the following real-world scenarios best illustrates the concept of electric flux?

Accepted Answer

The number of rain drops passing through an open window at an angle.

Question 15

A flat surface of area $$A is $$placed edge-on to a uniform electric field $$E. $$What is the electric flux through the surface?

Accepted Answer

$$\Phi_E = 0$$

Question 16

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

Accepted Answer

Calculating the electric field outside a uniformly charged sphere.

Question 17

A charged conductor is placed in an electric field. Where is the charge located?

Accepted Answer

Located on the surface of the conductor.

Question 18

Which of the following best explains why the net electric flux through a closed surface is independent of the surface's size?

Accepted Answer

Because the number of field lines passing through the surface depends only on the enclosed charge.

Question 19

A box contains two point charges: $$+q$$ and $$-q. $$What is the net electric flux through the surface of the box?

Accepted Answer

$$\Phi_E = 0$$

Study Notes: Electric Flux and Gauss's Law (University Physics, Chapter 22)

Study Guide - Practice Questions

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