Q: What is the magnitude of the charge of a single electron?

$$1.60 \times 10$$^{-19}$$\ \mathrm{C}$$

Q: A neutral sodium atom (Na) contains 11 protons. What is the total positive charge in one mole of sodium atoms? (Avogadro's number $$N_A = 6.02 \times 10$$^{23}$$)

$$1.06 \times 10$$^{5}$$\ \mathrm{C}$$

Question 1

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

Accepted Answer

The total electric charge in the universe remains constant; it is conserved in all processes.

Question 2

A glass rod is rubbed with silk and becomes positively charged. What happens at the atomic level to cause this?

Accepted Answer

Electrons are transferred from the glass rod to the silk.

Question 3

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

Accepted Answer

Copper

Question 4

What is the magnitude of the charge of a single electron?

Accepted Answer

$$1.60 	imes 10$$^{-19}$$\ \mathrm{C}$$

Question 5

A neutral sodium atom (Na) contains 11 protons. What is the total positive charge in one mole of sodium atoms? (Avogadro's number $$N_A = 6.02 	imes 10$$^{23}$$)

Accepted Answer

$$1.06 	imes 10$$^{5}$$\ \mathrm{C}$$

Question 6

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

They have free electrons that can move throughout the material.

Question 7

According to Coulomb’s Law, what happens to the force between two point charges if the distance between them is doubled?

Accepted Answer

The force becomes one-fourth as great.

Question 8

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 9

A point charge $$q = 2.0\ \mu\mathrm{C} is $$placed 0.50 m from another point charge $$Q = -3.0\ \mu\mathrm{C}. $$What is the magnitude of the force between them? ($$k = 8.99 	imes 10^9$\ \mathrm{N\cdot m^2$/C^2$$}$)

Accepted Answer

$$0.216\ \mathrm{N}$$

Question 10

Which of the following is true about the electric force between two charges according to Newton’s third law?

Accepted Answer

The force on each charge is equal in magnitude and opposite in direction.

Question 11

A neutral object is attracted to a charged rod. What is the most likely explanation for this attraction?

Accepted Answer

The neutral object becomes polarized, with its charges rearranged.

Question 12

Which of the following statements about electric charge is correct?

Accepted Answer

Electric charge is quantized in units of $$e.$$

Question 13

A sphere of radius $$R = 0.12\ \mathrm{m}$$ has a uniform surface charge density $$\sigma = 0.55\ \mathrm{C/m^2$}. $$What is the total charge on the sphere?

Accepted Answer

$$0.099\ \mathrm{C}$$

Question 14

If a point charge is placed outside a uniformly charged insulating sphere, how can the force between them be calculated?

Accepted Answer

By treating the sphere as if all its charge were concentrated at its center.

Question 15

Which of the following is a property of insulators?

Accepted Answer

Their electrons seldom move from atom to atom.

Question 16

Which Maxwell equation relates the electric field to the charge density in electrostatics?

Accepted Answer

$$
abla \cdot \mathbf{E} = \frac{ho}{\$$varepsilon_0$$}$$

Question 17

Which of the following best describes the superposition principle in electrostatics?

Accepted Answer

The net electric force on a charge is the sum of the individual forces from all other charges.

Question 18

A semiconductor differs from a conductor in that:

Accepted Answer

Its conductivity can be changed by chemical composition or external conditions.

Question 19

Which of the following is a real-world application of polarization in materials?

Accepted Answer

The attraction of small neutral pieces of paper to a charged comb.

Electric Charges, Forces, and Fields (Physics Ch. 19.1–19.3 Study Notes)

Guida di studio - Domande di pratica

Study guide - Flashcard