Question 1

Which of the following statements best describes the process of charging an object by induction?

Accepted Answer

A charged object is brought near a neutral object, causing a redistribution of charges within the neutral object, and then the neutral object is grounded to allow charge transfer.

Question 2

A small metal sphere is initially neutral. A negatively charged rod is brought close (but does not touch) to the sphere, and the sphere is then grounded. What is the final charge on the sphere after the ground connection is removed and the rod is taken away?

Accepted Answer

The sphere is left with a net positive charge.

Question 3

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

Accepted Answer

Copper

Question 4

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

Accepted Answer

The force is reduced to one-fourth its original value.

Question 5

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

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

Question 6

A positively charged rod is brought near small bits of paper, which are initially neutral. The paper is attracted to the rod. What is the best explanation for this phenomenon?

Accepted Answer

The charges in the paper are polarized, with negative charges attracted toward the rod and positive charges repelled.

Question 7

Which of the following statements about electric field lines is correct?

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

Which of the following is a property of conductors in electrostatic equilibrium?

Accepted Answer

Any excess charge resides entirely on the surface.

Question 10

A Van de Graaff generator is used to accumulate charge on a large dome. What is the primary reason the charge resides on the outer surface of the dome?

Accepted Answer

The electric field inside the conductor is zero, so charges move to the surface to maximize separation.

Question 11

Which of the following best describes the superposition principle as it applies to electric forces?

Accepted Answer

The net force on a charge is the vector sum of the forces exerted by all other charges present.

Question 12

A small oil droplet in the Millikan oil-drop experiment is suspended motionless between two charged plates. Which of the following is true at this moment?

Accepted Answer

The electric force on the droplet is equal in magnitude and opposite in direction to the gravitational force.

Question 13

Which of the following equations gives the electric flux $$\Phi_E$$ through a flat surface of area $$A in a $$uniform electric field $$E at an $$angle $$	heta to $$the normal of the surface?

Accepted Answer

$$\Phi_E = EA \cos 	heta$$

Question 14

A spherical conducting shell carries a net positive charge. What is the electric field inside the shell?

Accepted Answer

It is zero everywhere inside the shell.

Question 15

Which of the following statements about Gauss’s Law is correct?

Accepted Answer

The net electric flux through a closed surface equals the net charge enclosed divided by the permittivity of free space.

Question 16

A parallel plate capacitor has plates of area $$A$$ separated by distance $$d$$ and carries charge $$+Q$$ and $$-Q. $$What is the magnitude of the electric field $$E$$ between the plates (neglecting edge effects)?

Accepted Answer

$$E = \frac{Q}{\$$varepsilon_0$$ A}$$

Question 17

Which of the following is a correct statement about the conservation of electric charge?

Accepted Answer

Electric charge is always conserved; it can only be transferred from one object to another.

Question 18

A charged conductor has a sharp point. What happens to the surface charge density at this location, and why?

Accepted Answer

The surface charge density is higher at the sharp point because the radius of curvature is small.

Question 19

A test charge $$q_0 is $$placed in an electric field $$E$$ created by a source charge $$Q. $$What is the force $$F$$ experienced by the test charge?

Accepted Answer

$$F = q_0$ E$$

Electric Charge, Forces, and Fields: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard