Question 1

Which of the following statements best describes the process of charging by friction, as demonstrated by rubbing a plastic rod with wool?

Accepted Answer

Electrons are transferred from the wool to the plastic rod, giving the rod a net negative charge.

Question 2

A glass rod is rubbed with silk and then brought near a hanging plastic rod that was rubbed with wool. What is the expected interaction between the two rods?

Accepted Answer

They attract each other because they have opposite types of charge.

Question 3

Which of the following best explains why a charged comb can pick up small pieces of paper?

Accepted Answer

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

Question 4

Which of the following is a correct statement about conductors and insulators?

Accepted Answer

Conductors allow charge to move freely, while insulators keep charge fixed in place.

Question 5

A neutral metal sphere is touched by a negatively charged plastic rod. What happens to the sphere?

Accepted Answer

The sphere becomes negatively charged as electrons are transferred to it.

Question 6

Which of the following equations 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 7

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

Accepted Answer

The force decreases by a factor of 4.

Question 8

Which of the following best describes the electric field created by a positive point charge?

Accepted Answer

The electric field points radially outward from the charge.

Question 9

A small positive test charge is placed in an electric field. The direction of the electric field at that point is:

Accepted Answer

The same as the direction of the force on the test charge.

Question 10

Which of the following is the correct formula for the electric field $$E at a $$distance $$r$$ from a point charge $$q$$?

Accepted Answer

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

Question 11

A neutral atom becomes a positive ion when:

Accepted Answer

It loses one or more electrons.

Question 12

Which of the following statements about charge polarization is correct?

Accepted Answer

Polarization is a slight separation of positive and negative charges within a neutral object.

Question 13

Two identical metal spheres are touching. A negatively charged rod is brought near (but not touching) one sphere, and the spheres are then separated. What is the resulting charge on the spheres?

Accepted Answer

One sphere is negatively charged, and the other is positively charged.

Question 14

Which of the following is NOT a property of electric charge?

Accepted Answer

Charge is created and destroyed in chemical reactions.

Question 15

A charged rod is brought near, but does not touch, a neutral metal sphere. The sphere is then grounded (touched by a finger) while the rod is still nearby. What is the net charge on the sphere after the rod is removed?

Accepted Answer

The sphere has a net charge opposite to that of the rod.

Question 16

Which of the following best describes the relationship between the electric force and the electric field?

Accepted Answer

$$\vec{F} = q \vec{E}$$

Question 17

A student claims that a neutral object cannot be attracted to a charged object. Which of the following best refutes this claim?

Accepted Answer

A charged object can polarize a neutral object, resulting in an attractive force.

Question 18

Which of the following is the value of the fundamental unit of charge $$e$$?

Accepted Answer

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

Question 19

A point charge $$Q is $$placed at the origin. What is the direction of the electric field at a point located on the positive $$x-$$axis?

Accepted Answer

Away from the origin if $$Q is $$positive, toward the origin if $$Q is $$negative.

Electric Charges and Forces: Study Notes for Physics College Students

Guida di studio - Domande di pratica

Study guide - Flashcard