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

$$+1.6 \times 10$$^{-19}$$\ \mathrm{C}$$

Q: A small object carrying a charge of $$-8.00\ \mathrm{nC} is $$acted upon by a downward force of $$20.0\ \mathrm{nN} in an $$electric field. What is the magnitude and direction of the electric field?

$$E = 2.50 \times 10$$^{3}$$\ \mathrm{N/C}$$, upward

Q: Two small spheres, each with charge $$q$$, are separated by $$0.20\ \mathrm{m}$$ and repel each other with a force of $$4.57 \times 10$$^{-21}$$\ \mathrm{N}. $$What is the value of $$q$$? ($$k = 8.99 \times 10^9$\ \mathrm{N\cdot m^2$/C^2$$}$)

$$q = 1.01 \times 10$$^{-15}$$\ \mathrm{C}$$

Question 1

Which of the following best explains why lightning can destroy electronic devices such as computer chips?

Accepted Answer

Lightning produces a large static electric discharge, which can induce high voltages and currents in electronic circuits, damaging sensitive components.

Question 2

A plastic rod is rubbed with fur and becomes negatively charged. What happens at the atomic level to cause this?

Accepted Answer

Electrons are transferred from the fur to the rod.

Question 3

Which of the following statements about conductors and insulators is correct?

Accepted Answer

Conductors allow electric charge to move freely, while insulators do not.

Question 4

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

Accepted Answer

$$+1.6 	imes 10$$^{-19}$$\ \mathrm{C}$$

Question 5

Which equation correctly expresses the quantization of electric charge?

Accepted Answer

$$q = n e$$

Question 6

Two point charges, $$q_1$$ and $$q_2$$, are separated by a distance $$r. $$According to Coulomb’s law, what is the magnitude of the force between them?

Accepted Answer

$$F = k \dfrac{q_1$ q_2$}{r^2$}$$

Question 7

A large plastic block has a net charge of $$-1.0\ \mu\mathrm{C}. $$How many excess electrons does it have? ($$e = 1.6 	imes 10$$^{-19}$$\ \mathrm{C})$$

Accepted Answer

$$6.25 	imes 10$$^{12}$$

Question 8

In the Bohr model of the hydrogen atom, the electron orbits the proton at a distance $$r = 5.29 	imes 10$$^{-11}$$\ \mathrm{m}. $$What is the magnitude of the electric force between the electron and proton?

Accepted Answer

$$F = k \dfrac{e^2$}{r^2$}$$

Question 9

A small object carrying a charge of $$-8.00\ \mathrm{nC} is $$acted upon by a downward force of $$20.0\ \mathrm{nN} in an $$electric field. What is the magnitude and direction of the electric field?

Accepted Answer

$$E = 2.50 	imes 10$$^{3}$$\ \mathrm{N/C}$$, upward

Question 10

Which of the following best describes the direction of electric field lines?

Accepted Answer

They point away from positive charges and toward negative charges.

Question 11

A point charge $$q$$ produces an electric field at a distance $$r. $$What is the magnitude of the electric field?

Accepted Answer

$$E = k \dfrac{q}{r^2$}$$

Question 12

A charged particle of mass $$m$$ and charge $$q is $$placed in a uniform electric field $$E. $$What is its acceleration?

Accepted Answer

$$a = \dfrac{qE}{m}$$

Question 13

Which of the following is a correct statement of the law of conservation of charge?

Accepted Answer

The total electric charge in a closed system is constant; charge can neither be created nor destroyed.

Question 14

A negatively charged rod is brought near an uncharged metal ball, and the ball is then grounded. What is the final charge on the ball after the rod and ground are removed?

Accepted Answer

The ball is positively charged.

Question 15

Two small spheres, each with charge $$q$$, are separated by $$0.20\ \mathrm{m}$$ and repel each other with a force of $$4.57 	imes 10$$^{-21}$$\ \mathrm{N}. $$What is the value of $$q$$? ($$k = 8.99 	imes 10^9$\ \mathrm{N\cdot m^2$/C^2$$}$)

Accepted Answer

$$q = 1.01 	imes 10$$^{-15}$$\ \mathrm{C}$$

Question 16

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

Accepted Answer

The total electric field at a point is the vector sum of the electric fields produced by each charge individually.

Question 17

A proton is placed in a uniform electric field of $$1.0 	imes 10^4$\ \mathrm{N/C}$$ directed upward. What is the magnitude and direction of the force on the proton?

Accepted Answer

$$1.6 	imes 10$$^{-15}$$\ \mathrm{N}$$, upward

Question 18

Which of the following is true about electric field lines between two parallel plates with opposite charges?

Accepted Answer

The field lines are parallel and equally spaced, indicating a uniform electric field.

Electric Charge and Electric Field: Core Concepts and Applications

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