Q: What is the value of the proportionality constant $$k in $$Coulomb’s Law?

$$k = 8.988 \times 10^9$ \ \mathrm{N \cdot m^2$ / C^2$}$$

Q: Which equation represents Gauss’s Law for a closed surface?

$$\oint \vec{E} \cdot d\vec{A} = \frac{Q_{\text{encl}}}{\$$varepsilon_0$$}$$

Question 1

Which of the following statements best describes the principle of conservation of electric charge?

Accepted Answer

The arithmetic sum of the total charge in any interaction remains constant.

Question 2

A glass rod is rubbed with silk, causing electrons to transfer from the rod to the silk. What is the resulting charge on the glass rod?

Accepted Answer

The glass rod becomes positively charged.

Question 3

Which equation correctly expresses Coulomb’s Law for the magnitude of the force between two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r$$?

Accepted Answer

$$F = k \frac{q_1$ q_2$}{r^2$}$$

Question 4

A neutral metal sphere is brought near a negatively charged rod but does not touch it. What happens to the charges in the sphere?

Accepted Answer

Electrons in the sphere move away from the rod, causing charge separation.

Question 5

Which of the following materials is most likely to be a good conductor?

Accepted Answer

Copper

Question 6

What is the value of the proportionality constant $$k in $$Coulomb’s Law?

Accepted Answer

$$k = 8.988 	imes 10^9$ \ \mathrm{N \cdot m^2$ / C^2$}$$

Question 7

A point charge $$q$$ creates an electric field at a distance $$r. $$Which equation gives the magnitude of the electric field?

Accepted Answer

$$E = k \frac{q}{r^2$}$$

Question 8

If three point charges are placed at the vertices of an equilateral triangle, how do you determine the net force on one of the charges?

Accepted Answer

Add the forces from the other two charges as vectors.

Question 9

Which statement about electric field lines is correct?

Accepted Answer

The density of field lines is proportional to the magnitude of the electric field.

Question 10

A charged electroscope is used to determine the sign of an unknown charge. What happens if a positively charged object is brought near the electroscope?

Accepted Answer

The leaves of the electroscope spread further apart.

Question 11

What is the electric field inside a good conductor in electrostatic equilibrium?

Accepted Answer

It is zero.

Question 12

Which formula expresses the electric flux $$\Phi_E$$ through a surface of area $$A$$ with electric field $$E at an $$angle $$	heta to $$the normal?

Accepted Answer

$$\Phi_E = EA \cos 	heta$$

Question 13

Gauss’s Law relates the net electric flux through a closed surface to which physical quantity?

Accepted Answer

The net electric charge enclosed by the surface.

Question 14

Which equation represents Gauss’s Law for a closed surface?

Accepted Answer

$$\oint \vec{E} \cdot d\vec{A} = \frac{Q_{	ext{encl}}}{\$$varepsilon_0$$}$$

Question 15

A DNA molecule is held together by electrostatic forces between nucleotide bases. Which pairs are attracted to each other?

Accepted Answer

A and T, G and C

Question 16

A photocopy machine uses electrostatic principles to transfer toner to paper. What is the role of the charged drum?

Accepted Answer

It attracts toner particles to the areas that remain charged after exposure to light.

Question 17

Two point charges, $$+2 \ \mu\mathrm{C}$$ and $$-3 \ \mu\mathrm{C}$$, are placed 0.5 m apart. What is the direction of the force on the $$+2 \ \mu\mathrm{C}$$ charge?

Accepted Answer

Toward the $$-3 \ \mu\mathrm{C}$$ charge (attractive)

Question 18

Which of the following best describes the quantization of electric charge?

Accepted Answer

Charge exists only in integer multiples of the elementary charge $$e.$$

Question 19

A parallel plate capacitor has two closely spaced, oppositely charged plates. What is the electric field between the plates?

Accepted Answer

It is constant and directed from the positive to the negative plate.

Question 20

A $$1 \ \mu\mathrm{C}$$ charge is placed in an electric field of $$2 	imes 10^5$ \ \mathrm{N/C}. $$What is the magnitude of the force on the charge?

Accepted Answer

$$F = 0.2 \ \mathrm{N}$$

Electric Charge and Electric Field: Study Notes (Chapter 16)

Study Guide - Practice Questions

Study Guide - Flashcards