1. Most objects are neutral.
2. Most objects have positive charge only.
3. Most objects have negative charge only.
4. Most objects have excess protons.

1. No, an insulator cannot charge a conductor by induction.
2. No, an insulating material cannot charge a conductor.
3. Yes, an uncharged insulator can charge a conductor by induction.
4. Yes, a charged insulator can charge a conductor upon contact.

True or false—A liquid can be an insulating material.

1. true
2. false

If you dive into a pool of seawater through which an equal amount of positively and negatively charged particles is moving, will you receive an electric shock?

1. Yes, because negatively charged particles are moving.
2. No, because positively charged particles are moving.
3. Yes, because positively and negatively charged particles are moving.
4. No, because equal amounts of positively and negatively charged particles are moving.

True or false—The high-voltage wires that you see connected to tall metal-frame towers are held aloft by insulating connectors, and these wires are wrapped in an insulating material.

1. true
2. false

By considering the molecules of an insulator, explain how an insulator can be overall neutral but carry a surface charge when polarized.

1. Inside the insulator, the oppositely charged ends of the molecules cancel each other.
2. Inside the insulator, the oppositely charged ends of the molecules do not cancel each other.
3. The electron distribution in all the molecules shifts in every possible direction, leaving an excess of positive charge on the opposite end of each molecule.
4. The electron distribution in all the molecules shifts in a given direction, leaving an excess of negative charge on the opposite end of each molecule.

A dust particle acquires a charge of −13 nC. How many excess electrons does it carry?

1. 20.8 × 10⁻²⁸ electrons
2. 20.8 × ⁻¹⁹ electrons
3. 8.1 × 10¹⁰ electrons
4. 8.1 × 10¹⁹ electrons

Two identical conducting spheres are charged with a net charge of +5.0 q on the first sphere and a net charge of −8.0 q on the second sphere. The spheres are brought together, allowed to touch, and then separated. What is the net charge on each sphere now?

1. −3.0q
2. −1.5q
3. +1.5q
4. +3.0q

Two plastic spheres with uniform charge repel each other with a force of 10 N . If you remove the charge from one sphere, what will be the force between the spheres?

1. The force will be 15 N.
2. The force will be 10 N.
3. The force will be 5 N.
4. The force will be zero.

What creates a greater magnitude of force, two charges +q a distance r apart or two charges – q the same distance apart?

1. Two charges +q a distance r away
2. Two charges −q a distance r away
3. The magnitudes of forces are equal.

In Newton’s law of universal gravitation, the force between two masses is proportional to the product of the two masses. What plays the role of mass in Coulomb’s law?

1. the electric charge
2. the electric dipole
3. the electric monopole
4. the electric quadruple

In terms of Coulomb’s law, why are water molecules attracted by positive and negative
charges?

1. Water molecules are neutral.
2. Water molecules have a third type of charge that is attracted by positive as well as negative charges.
3. Water molecules are polar.
4. Water molecule have either an excess of electrons or an excess of protons.

1. The area of the cloud that was struck by lightning had a positive charge.
2. The area of the cloud that was struck by lightning had a negative charge.
3. The area of the cloud that was struck by lightning is neutral.
4. The area of the cloud that was struck by lightning had a third type of charge.

Two particles with equal charge experience a force of 10 nN when they are 30 cm apart. What is the magnitude of the charge on each particle?

1. −5.8 × 10⁻¹⁰ C
2. −3.2 × 10⁻¹⁰ C
3. +3.2 × 10⁻¹⁰ C
4. +1.4 × 10⁻⁵ C

Three charges are on a line. The left charge is q₁ = 2.0 nC . The middle charge is q₂ = 5.0 nC . The right charge is q₃ = − 3.0 nC . The left and right charges are 2.0 cm from the middle charge. What is the force on the middle charge?

1. −5.6 × 10⁻⁴ N to the left
2. −1.12 × 10⁻⁴ N to the left
3. +1.12 × 10⁻⁴ N to the right
4. 5.6 × 10⁻⁴ N to the right

Why can electric fields not cross each other?

1. Many electric-field lines can exist at any given point in space.
2. No electric-field lines can exist at any given point in space.
3. Only a single electric-field line can exist at any given point in space.
4. Two electric-field lines can exist at the same point in space.

A constant electric field is (4.5 × 10⁵ N/C)ŷ. In which direction is the force on a −20 nC charge placed in this field?

1. The direction of the force is in the $+\widehat{x}$ direction.
2. The direction of the force is in the $+\widehat{x}$ direction.
3. The direction of the force is in the −ŷ direction.
4. The direction of the force is in the +ŷ direction.

An arbitrary electric field passes through a box-shaped volume. There are no charges in the box. If 11 electric-field lines enter the box, how many electric-field lines must exit the box?

1. nine electric field lines
2. 10 electric field lines
3. 11 electric field lines
4. 12 electric field lines

In a science-fiction movie, a villain emits a radial electric field to repulse the hero. Knowing that the hero is electrically neutral, is this possible? Explain your reasoning.

1. No, because an electrically neutral body cannot be repelled or attracted.
2. No, because an electrically neutral body can be attracted but not repelled.
3. Yes, because an electrically neutral body can be repelled or attracted.
4. Yes, because an electrically neutral body can be repelled.

An electric field (15 N/C)ẑ applies a force (− 3 × 10^–6 N)ẑ on a particle. What is the charge on the particle?

1. −2.0 × 10^–7 C
2. 2.0 × 10^–7 C
3. 2.0 × 10^–8 C
4. 2.0 × 10^–9 C

Two uniform electric fields are superimposed. The first electric field is ${\overrightarrow{\text{E}}}_{\text{1}}\text{ = (14}\text{ N/C)}\widehat{x}$ . The second electric field is ${\overrightarrow{\text{E}}}_{\text{2}}\text{ = (7}\text{.0 N/C)}ŷ$ . With respect to the positive x axis, at which angle will a positive test charge accelerate in this combined field?

1. 27°
2. 54°
3. 90°
4. 108°

True or false—The potential from a group of charges is the sum of the potentials from each individual charge.

1. false
2. true

True or false—The characteristics of an electric field make it analogous to the gravitational field near the surface of Earth.

1. false
2. true

1. It moves toward regions of higher potential because its charge is negative.
2. It moves toward regions of lower potential because its charge is negative
3. It moves toward regions of higher potential because its charge is positive.
4. It moves toward regions of lower potential because its charge is positive.

What is the relationship between voltage and energy? More precisely, what is the relationship between potential difference and electric potential?

1. Voltage is the energy per unit mass at some point in space.
2. Voltage is the energy per unit length in space.
3. Voltage is the energy per unit charge at some point in space.
4. Voltage is the energy per unit area in space.

Three parallel plates are stacked above each other, with a separation between each plate. If the potential difference between the first two plates is ΔV₁ and the potential between the second two plates is ΔV₂ , what is the potential difference between the first and the third plates?

1. ΔV₃ = ΔV₂ + ΔV₁
2. ΔV₃ = ΔV₂ − ΔV₁
3. ΔV₃ = ΔV₂ / ΔV₁
4. ΔV₃ = ΔV₂×ΔV₁

You move a charge q from r_i = 20 cm to r_f = 40 cm from a fixed charge Q = 10 nC. What is the difference in potential for these two positions?

1. −2.2 × 10² V
2. −1.7 × 10³ V
3. −2.2 × 10⁴ V
4. −1.7 × 10² V

How much work is required from an outside agent to move an electron from x_i = 0 to x_f = 20 cm in an electric field $(50\text{N/C})\widehat{x}$ ?

1. 1.6 × 10⁻¹⁵ J
2. 1.6 × 10⁻¹⁶ J
3. 1.6 × 10⁻²⁰ J
4. 1.6 × 10⁻¹⁸ J

You insert a dielectric into an air-filled capacitor. How does this affect the energy stored in the capacitor?

1. Energy stored in the capacitor will remain same.
2. Energy stored in the capacitor will decrease.
3. Energy stored in the capacitor will increase.
4. Energy stored in the capacitor will increase first, and then it will decrease.

True or false— Placing a dielectric between the plates of a capacitor increases the energy of the capacitor.

1. false
2. true

True or false— The electric field in an air-filled capacitor is reduced when a dielectric is inserted between the plates.

1. false
2. true