BASIC HISTORY & FOUNDATIONAL CONCEPTS OF ELECTRICITY
Who first called the mysterious force produced by rubbing materials the “electric force”?
a. William Gilbert
b. Isaac Newton
c. Benjamin Franklin
d. Aristotle
e. Marie Curie
a. William Gilbert
William Gilbert first used the term “electric force” because he was the earliest to study and name electrical effects scientifically.
Which particle plays no role in electricity because it has no electric charge?
a. proton
b. electron
c. neutron
d. photon
e. ion
c. neutron
The neutron plays no role in electricity because it has no charge and therefore doesn’t interact electrically.
When you rub cloth on a glass rod, why does the glass rod become positively charged?
a. The glass rod gains protons.
b. The glass rod gains neutrons.
c. The glass rod loses electrons.
d. The glass rod loses protons.
e. The glass rod gains electrons.
c. The glass rod loses electrons.
A glass rod becomes positively charged when rubbed because it loses electrons, leaving excess positive charge behind.
Copper is commonly used in electrical wires because it ____________________.
a. is lightweight and flexible
b. prevents heat from escaping
c. is a good conductor because its outer electrons move freely
d. has no electrons in its outer shell
e. is an insulator that blocks electricity
c. is a good conductor because its outer electrons move freely
Copper is used in wiring because its loosely bound outer electrons move freely, making it an excellent conductor.
What is the meaning of the Greek word “atom”?
a. invisible
b. indivisible
c. smallest piece
d. element
e. matter
b. indivisible
The Greek word “atom” means “indivisible” because ancient philosophers believed matter could not be divided beyond a smallest piece.
Which type of charge does an electron have?
a. negative
b. positive
c. neutral
d. variable
e. zero
a. negative
An electron has a negative charge, which is why it is attracted to positive charges and repelled by other electrons.
How does the electric force FE relate to the charge q and electric field E?
a. FE = mE
b. FE = qq
c. FE = q/E
d. FE = qE
e. FE = kq/r2
d. FE = qE
The electrical force equation FE = qE shows that electric force is directly proportional to both charge and electric field strength.
If you add extra electrons to a metal sphere, where will these extra electrons end up?
a. spread throughout the inside of the sphere
b. clustered at the center of the sphere
c. evenly distributed on the sphere’s surface
d. gathered at one corner of the sphere
e. concentrated at the bottom of the sphere due to gravity
c. evenly distributed on the sphere’s surface
Extra electrons on a metal sphere spread evenly over the surface because they repel each other and seek maximum separation.
According to ancient Western thought, which of the following was NOT one of the four basic elements?
a. Hydrogen
b. Fire
c. Water
d. Air
e. Earth
a. Hydrogen
Hydrogen was not one of the ancient four elements because those early models only included earth, air, fire, and water.
What is the charge of a proton?
a. neutral
b. negative
c. zero
d. variable
e. positive
e. positive
A proton has a positive charge, making it the opposite of an electron’s negative charge.
Which statement below BEST explains what happens to the electric field at the point exactly between two protons that are the same distance apart?
a. It doubles in strength.
b. It points to the right.
c. It points to the left.
d. It cancels out and becomes zero.
e. It becomes negative.
d. It cancels out and becomes zero.
The electric field between two identical protons cancels to zero at the midpoint because their equal but opposite-direction fields balance perfectly.
A car struck by lightning protects the passengers inside mainly because the
a. metal frame acts as a Faraday cage with zero electric field inside
b. windows block the electricity
c. tires absorb the lightning
d. car’s paint deflects the charge
e. steering wheel is made of plastic
a. metal frame acts as a Faraday cage with zero electric field inside
A car protects passengers from lightning because its metal body acts as a Faraday cage with zero electric field inside.
What did some ancient philosophers believe about dividing matter?
a. that you could keep cutting it into smaller pieces forever
b. that everything was made only of hydrogen and oxygen
c. that atoms were made of fire and water
d. that matter could not be divided at all
e. that all matter was made of feathers and paper
a. that you could keep cutting it into smaller pieces forever
Some ancient philosophers thought you could divide matter forever, believing there was no smallest unit.
Which statement BEST explains why electrons orbit the nucleus rather than the other way around?
a. The nucleus has a larger charge.
b. The electron has greater mass.
c. The proton has much greater mass than the electron, so the electron accelerates more.
d. The nucleus spins faster.
e. The electron has no inertia.
c. The proton has much greater mass than the electron, so the electron accelerates more.
Electrons orbit the nucleus because the much larger proton mass causes the lighter electron to accelerate more in response to electric force.
Which statement BEST explains why your hairs stand on end after touching the metal sphere of a Van de Graff generator?
a. Gravity pulls the hair upward.
b. Air pressure forces the hair apart.
c. The strands become negatively charged and repel each other.
d. The strands become positively charged and attract each other.
e. Heat causes the hair to rise.
c. The strands become negatively charged and repel each other.
Hair stands up near a Van de Graaff generator because each strand becomes negatively charged and repels the others.
What happens to the electric field inside a charged conductor?
a. It becomes stronger at the center.
b. It points toward the surface.
c. It increases near the corners.
d. It circles around the outer edges.
e. It is zero everywhere inside.
e. It is zero everywhere inside.
The electric field inside a charged conductor is zero everywhere because charges rearrange themselves to cancel internal fields.