Question 1

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

Accepted Answer

The total electric charge in an isolated system remains constant during any process.

Question 2

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

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 conductor of electricity?

Accepted Answer

Copper

Question 4

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

Accepted Answer

Negative charges in the sphere move away from the rod, and positive charges move toward the rod.

Question 5

Which equation correctly expresses Coulomb’s Law for 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 6

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

Accepted Answer

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

Question 7

A charged particle with charge $$q$$ and mass $$m is $$released from rest in a uniform electric field $$E. $$What is its acceleration?

Accepted Answer

$$a = \frac{qE}{m}$$

Question 8

Which of the following best describes the electric field inside a conductor in electrostatic equilibrium?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 9

A thin ring of radius $$a$$ carries a total charge $$+Q$$ uniformly distributed. What is the electric field at a point on the axis of the ring, a distance $$x$$ from the center?

Accepted Answer

$$E = \frac{kQx}{(a^2$ + x^2$)^{3/2}$$}$

Question 10

Two parallel plates carry equal and opposite charges, creating a uniform electric field between them. If the surface charge density on each plate is $$\sigma$$, what is the magnitude of the electric field between the plates?

Accepted Answer

$$E = \frac{\sigma}{\$$epsilon_0$$}$$

Question 11

A small positive test charge is placed at a point where the electric field is directed to the right. What is the direction of the force on the test charge?

Accepted Answer

To the right

Question 12

Which of the following is a correct statement about electric field lines?

Accepted Answer

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

Question 13

A charged electroscope is used to determine the sign of an unknown charge. If the leaves of the electroscope diverge further when the unknown charge is brought near, what can you conclude?

Accepted Answer

The unknown charge has the same sign as the electroscope.

Question 14

A particle with charge $$-e$$ and mass $$m is $$accelerated from rest through a potential difference $$V$$ between two parallel plates. What is its final speed $$v$$ when it exits the plates?

Accepted Answer

$$v = \sqrt{\frac{2eV}{m}}$$

Question 15

Which of the following is a real-world application of the concept of a Faraday cage?

Accepted Answer

A microwave oven's metal mesh door

Question 16

A uniformly charged disk of radius $$R$$ has a surface charge density $$\sigma. $$What is the electric field at a point on the axis of the disk, a distance $$z$$ above its center?

Accepted Answer

$$E = \frac{\sigma}{2\$$epsilon_0$$} \left(1 - \frac{z}{\sqrt{z^2$ + R^2$}}\right)$$

Question 17

If a small positive charge is placed at the center of a nonconducting ring carrying a uniformly distributed negative charge, and is displaced slightly along the axis, what happens?

Accepted Answer

The charge will continue to move away, indicating unstable equilibrium.

Question 18

Which of the following best explains why a person is safe inside a car during a lightning storm?

Accepted Answer

The metal body of the car acts as a Faraday cage, causing the electric field inside to be zero.

Electric Charge and Electric Field: Study Notes (Chapter 21, Giancoli)

Study Guide - Practice Questions

Study Guide - Flashcards