Question 1

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

Accepted Answer

The total electric charge in any closed system remains constant over time.

Question 2

A glass rod is rubbed with silk and then brought near a neutral metal ball suspended by an insulating thread. What will happen and why?

Accepted Answer

The ball will be attracted to the rod because the rod induces a separation of charge in the ball.

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 lithium atom has 3 protons, 4 neutrons, and 3 electrons. If it loses one electron, what is the resulting net charge?

Accepted Answer

+1 elementary charge

Question 5

Which of the following best explains why water is such a good solvent for ionic compounds like salt?

Accepted Answer

Water molecules are electric dipoles, so they can surround and stabilize both positive and negative ions.

Question 6

A negatively charged plastic rod is brought near, but does not touch, a neutral metal sphere on an insulating stand. The sphere is then grounded while the rod is still nearby. What is the final charge on the sphere after the rod is removed?

Accepted Answer

Positive

Question 7

Which of the following is true about electric field lines?

Accepted Answer

They never intersect and their density indicates the strength of the field.

Question 8

A point charge $$q$$ produces an electric field at a distance $$r. $$What is the magnitude of the electric field at that point?

Accepted Answer

$$E = \frac{1}{4 \pi \$$varepsilon_0$$} \frac{|q|}{r^2$}$$

Question 9

Which of the following best describes the behavior of a dipole in a uniform electric field?

Accepted Answer

It experiences zero net force but a nonzero torque.

Question 10

A charged comb can pick up small pieces of paper even though the paper is neutral. What is the best explanation for this phenomenon?

Accepted Answer

The electric field of the comb polarizes the molecules in the paper, creating an attractive force.

Question 11

Which of the following statements about conductors and insulators is correct?

Accepted Answer

Conductors allow free movement of electric charge, while insulators do not.

Question 12

Two point charges, $$q_1 = +2$$ \ \mu C$$ and q_2$ = -2 \ \mu C$$, are placed 0.5 m apart. What is the direction of the force on $$q_1$$ due to $$q_2$$?

Accepted Answer

Toward $$q_2 ($$attractive)

Question 13

If the distance between two point charges is doubled, how does the magnitude of the electrostatic force between them change?

Accepted Answer

It becomes one-fourth as large.

Question 14

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

Accepted Answer

Electrostatic painting, where charged paint droplets are attracted to a metal object.

Question 15

A positive test charge is placed in an electric field created by a negative point charge. In which direction does the force on the test charge point?

Accepted Answer

Toward the negative charge

Question 16

Which of the following best describes the superposition principle for electric fields?

Accepted Answer

The total electric field at a point is the vector sum of the electric fields produced by each charge.

Question 17

Which of the following is NOT a property of electric field lines?

Accepted Answer

They can cross each other.

Question 18

A water molecule is an electric dipole. What would happen to its ability to dissolve salt if it were not a dipole?

Accepted Answer

Water would be a poor solvent for salt, and many chemical reactions in solution would not occur.

Question 19

A charged object exerts a force on a neutral insulator. What is the mechanism responsible for this force?

Accepted Answer

Polarization of the molecules in the insulator.

Electric Charge and Electric Field: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards