Question 1

Which of the following statements 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 plastic rod is rubbed with wool and then brought near small pieces of paper. The rod attracts the paper. Which of the following best explains this observation?

Accepted Answer

The rod becomes negatively charged and induces a polarization in the paper, resulting in attraction.

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 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 one is positively charged and the other is negatively charged.

Question 5

Which of the following best describes the behavior of charge in a conductor versus an insulator?

Accepted Answer

Charge moves freely in conductors but remains fixed in insulators.

Question 6

A metal sphere is touched by a charged plastic rod. What happens to the charge on the sphere if it is connected to another metal sphere by a metal rod?

Accepted Answer

The charge is evenly distributed between both spheres.

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

What is the direction of the electric field at a point near a negative point charge?

Accepted Answer

Toward the negative charge.

Question 9

A parallel-plate capacitor creates a uniform electric field between its plates. Which equation gives the magnitude of this field if the plates carry charge $$Q$$ and have area $$A$$?

Accepted Answer

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

Question 10

Which of the following is true about the electric field inside a conductor in electrostatic equilibrium?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 11

A DNA fragment with negative charge is placed in a uniform electric field during gel electrophoresis. What is the direction of the force on the fragment?

Accepted Answer

Opposite to the direction of the electric field.

Question 12

Which of the following best describes the net force and torque on an electric dipole placed in a uniform electric field?

Accepted Answer

There is a net torque but no net force.

Question 13

If two point charges $$q_1$$ and $$q_2$$ are separated by a distance $$r$$, and the force between them is $$F$$, what will be the new force if the distance is doubled?

Accepted Answer

$$F_{new} = \frac{F}{4}$$

Question 14

Which of the following is a correct statement about polarization?

Accepted Answer

Polarization is the slight separation of positive and negative charges in a neutral object, resulting in attraction to a charged object.

Question 15

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 16

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

Accepted Answer

They can cross each other.

Question 17

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

Accepted Answer

Excess charge resides entirely on the surface of the conductor.

Question 18

A lightning rod is designed with a sharp point. What is the main reason for this design?

Accepted Answer

To increase the density of charge and electric field at the tip, allowing charge to dissipate into the air and reduce the likelihood of a lightning strike.

Question 19

Which of the following is true about the force between two charges according to Coulomb’s law?

Accepted Answer

The force can be either attractive or repulsive depending on the signs of the charges.

Electric Fields and Forces: Study Guide for Physics with Calculus

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