Question 1

Which of the following statements best describes why the leaves of a neutral electroscope move apart when a positively charged rod is brought close to (but does not touch) the sphere?

Accepted Answer

The electroscope is polarized by the rod; the sphere is negative and the leaves are positive.

Question 2

A positively charged rod is brought near a neutral metal sphere. What happens to the charges in the sphere?

Accepted Answer

Electrons in the sphere are attracted toward the rod, causing the near side to become negatively charged and the far side to become positively charged.

Question 3

Which of the following best describes the difference between conductors and insulators?

Accepted Answer

Conductors allow charge to move freely over long distances, while insulators only allow charge to move short (atomic) distances.

Question 4

Two metal spheres A and B are initially neutral and are touching. A positively charged rod is brought near to A without touching it. The spheres are then pulled apart and the rod is removed. What are the charges on A and B after this process is completed?

Accepted Answer

A is positive and B is negative

Question 5

Which equation correctly expresses Coulomb's Law for the force between two point charges?

Accepted Answer

$$F = \frac{1}{4\pi\$$varepsilon_0$$} \frac{q_1$ q_2$}{r^2$} \hat{r}$$

Question 6

What are the correct SI units for the constant $$K = \frac{1}{4\pi\$$varepsilon_0$$} in $$Coulomb's Law so that force $$F is in $$newtons?

Accepted Answer

$$N \cdot m^2$/C^2$

Question 7

A square has equal positive charges at three of its corners. What is the direction of the electric field at the fourth corner (point P)?

Accepted Answer

Direction 3

Question 8

A charge $$q = -2.0 nC is $$placed in a region where the electric field is $$\vec{E} = 1.08 \hat{i} + 1.07 \hat{j} N/C. $$What is the force on the charge?

Accepted Answer

$$(-6.0 \hat{i} + 4.0 \hat{j}) N$$

Question 9

Which of the following best describes the concept of charge polarization?

Accepted Answer

A slight separation of positive and negative charges occurs within a neutral object.

Question 10

Consider two uniformly charged spheres, with $$0 \u003c Q_{left} \u003c Q_{right}. $$Which pair of vectors best represents the forces on the two spheres?

Accepted Answer

Option (e)

Question 11

For the three charges shown: $$A: +3 C$$, $$B: -3 C$$, $$C: +1 C$$, which diagram best represents the forces from A and B on charge C?

Accepted Answer

Option (c)

Question 12

Which of the following is a correct statement about the superposition principle in electrostatics?

Accepted Answer

The net force on a charge is the sum of the forces from each individual charge, calculated independently.

Question 13

A plastic rod is rubbed with silk, leaving the rod negatively charged. What does this tell you about the movement of electrons?

Accepted Answer

Electrons moved from the silk to the rod.

Question 14

Which of the following best describes the electric field at a point in space?

Accepted Answer

The electric field is the force per unit charge at that point.

Question 15

A weather map shows wind velocity as a vector field. Which of the following is a correct analogy to the electric field?

Accepted Answer

The electric field, like wind velocity, has both magnitude and direction at every point in space.

Question 16

A conductor is charged by contact with a plastic rod. What happens to the excess charge?

Accepted Answer

The excess charge spreads out over the surface of the conductor.

Question 17

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

Accepted Answer

Electric charge exists only in integer multiples of the elementary charge $$e = 1.60 	imes 10$$^{-19}$$ C.

Question 18

If the force between two charges is attractive, what can you conclude about the signs of the charges?

Accepted Answer

The charges have opposite signs.

Question 19

A neutral insulator is polarized by a nearby positive charge. What is the net force on the insulator?

Accepted Answer

The net force is zero because the insulator is neutral.

Electric Charges and Forces: Study Notes Ch 22

Study Guide - Practice Questions

Study Guide - Flashcards