Question 1

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

Accepted Answer

Charge is neither created nor destroyed, only transferred from one place to another.

Question 2

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

Accepted Answer

The rod has lost electrons to the silk.

Question 3

Which material is most likely to allow charge to move freely through it?

Accepted Answer

Copper

Question 4

A neutral sphere is brought near a positively charged rod, but does not touch it. What happens to the charges in the sphere?

Accepted Answer

Negative charges in the sphere are attracted toward the rod, and positive charges are repelled away from the rod.

Question 5

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 6

If the distance between two point charges is doubled, what happens to the magnitude of the electrostatic force between them?

Accepted Answer

It becomes one-fourth as large.

Question 7

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

Accepted Answer

Electric field lines start on positive charges and end on negative charges.

Question 8

A parallel-plate capacitor creates a uniform electric field between its plates. Which of the following best describes the direction of the electric field?

Accepted Answer

From the positive plate to the negative plate.

Question 9

A metal sphere is placed in a region with a strong external electric field and reaches electrostatic equilibrium. What is the electric field inside the sphere?

Accepted Answer

It is zero.

Question 10

A bee uses electric fields to locate flowers. Which of the following best explains how this is possible?

Accepted Answer

Flowers and bees have different electric potentials, creating detectable electric fields.

Question 11

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 12

Which of the following best describes the behavior of excess charge on a conductor in electrostatic equilibrium?

Accepted Answer

It is found only on the surface of the conductor.

Question 13

A negative ion is formed when:

Accepted Answer

An atom gains an electron.

Question 14

Which of the following is true about the electric field at the surface of a charged conductor?

Accepted Answer

It is always perpendicular to the surface.

Question 15

A charged rod is brought near, but does not touch, a neutral metal sphere. What is the best explanation for why the sphere is attracted to the rod?

Accepted Answer

The rod induces a separation of charge in the sphere, creating an attractive force.

Question 16

Which of the following best describes the electric field inside a cell membrane, given that it is typically $$10^7 N/C$$?

Accepted Answer

It is much stronger than the field near a charged object by rubbing.

Question 17

A lightning rod is designed with a sharp point. Why is this effective in reducing the likelihood of a lightning strike?

Accepted Answer

The sharp point increases the electric field strength, allowing excess charge to dissipate into the air.

Question 18

Which of the following is the correct expression for the force on a charge $$q in a $$known electric field $$\vec{E}$$?

Accepted Answer

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

Question 19

A parallel-plate capacitor has plates of area $$A$$ and charge $$Q. $$What is the surface charge density $$\sigma$$?

Accepted Answer

$$\sigma = \frac{Q}{A}$$

Electric Fields and Forces: Structured Study Notes for Physics with Calculus

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