Question 1

Which property of water molecules allows them to act as an effective solvent for ionic compounds in biological systems?

Accepted Answer

Their polarity, with a partial negative charge on oxygen and partial positive charges on hydrogen.

Question 2

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

Accepted Answer

The algebraic sum of all electric charges in any closed system is constant.

Question 3

A glass rod is rubbed with silk, and electrons are transferred from the glass to the silk. What is the resulting charge on the glass rod?

Accepted Answer

The glass rod becomes positively charged due to a deficiency of electrons.

Question 4

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

Accepted Answer

Copper

Question 5

A neutral lithium atom has 3 protons, 4 neutrons, and 3 electrons. If it loses one electron, what is the resulting ion called and what is its net charge?

Accepted Answer

A positive ion with a net charge of $$+1e$$

Question 6

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

Accepted Answer

Redistribution of charges within an object due to the presence of a nearby charged object, without direct contact.

Question 7

Two point charges, $$q_1 = +2$$ \ \mu C$$ and q_2$ = -2 \ \mu C$$, are separated by a distance $$r = 0.5 \ m. $$What is the magnitude of the electric force between them? (Use $$k_e = 8.99 	imes 10^9$ \ N \cdot m^2$/C^2$)

Accepted Answer

$$F = 1.44 	imes 10^3$ \ N$$

Question 8

Which of the following is true about the electric force and gravitational force between two protons?

Accepted Answer

The electric force is much stronger than the gravitational force.

Question 9

Three charges are placed at the corners of a right triangle: $$q_1 = +5$$ \ \mu C$$, q_2$ = -2 \ \mu C$$, and $$q_3 = +5$$ \ \mu C$$. If q_3$ is at the right angle, what is the direction of the net force on q_3$?

Accepted Answer

Along the diagonal between $$q_1$$ and $$q_2$$

Question 10

A negatively charged comb can pick up small pieces of paper. What is the best explanation for this phenomenon?

Accepted Answer

The comb induces a separation of charge in the paper, causing attraction.

Question 11

A paint sprayer uses negatively charged paint droplets to coat a metal object. Why does this method improve the efficiency of painting?

Accepted Answer

The metal object is induced with a positive charge, attracting the negative paint droplets.

Question 12

Which of the following equations correctly expresses Coulomb’s Law for the magnitude of the electric 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 13

If you rub a balloon against your hair and the balloon becomes negatively charged, what happens to the mass of your hair?

Accepted Answer

It will increase.

Question 14

Three objects, A, B, and C, are brought close to each other. A and B repel, B and C repel, and A and C attract. Which combination of charge signs is possible?

Accepted Answer

A: +, B: +, C: -

Question 15

Which of the following best describes the principle of superposition for electric forces?

Accepted Answer

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

Question 16

A neutral object is brought near a negatively charged rod. What happens to the charges in the neutral object?

Accepted Answer

Electrons in the neutral object move away from the rod, causing polarization.

Question 17

Which of the following is NOT a fundamental force in nature?

Accepted Answer

Frictional force

Question 18

If two 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

$$F/4$$

Electric Charge and Coulomb’s Law: Foundations of Electrostatics

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