Electricity & Charge
When a balloon is rubbed against someone's hair, electrons move from the hair to the balloon. What charge does the balloon gain?
A negative charge
A student places iron filings around a bar magnet. The filings form a pattern. What does this pattern represent?
A magnetic field
A student wraps wire around an iron nail and connects the wire to a battery. What has the student created?
an electromagnet
What type of energy does a generator convert into electrical energy?
mechanical energy
Which of the following is part of the electromagnetic spectrum?
A. Sound waves
B. Water waves
C. Radio waves
D. Ocean currents
C, radio waves
After rubbing a balloon on her hair, Maria notices that her hair stands up and the balloon sticks to a wall. What caused these effects?
Static electricity caused by a buildup of electric charge
What is a magnetic field?
The region around a magnetic material where it can exert a magnetic force
What causes the iron nail to become magnetic in this experiment?
the electric current flowing through the wire creates a magnetic field
Power plants use turbines and generators. What happens when the turbines spin?
magnets move around coils of wire, generating electricity
Name three types of electromagnetic waves mentioned in the reading.
radio waves, microwaves, infrared, visible light, UV, X-rays, and gamma rays?
(Any three are acceptable.)
A balloon gains 50 additional electrons. Which statement is most accurate?
A. The balloon becomes positively charged.
B. The balloon becomes negatively charged.
C. The balloon becomes magnetic.
D. The balloon becomes electrically neutral.
B, the balloon becomes negatively charged
A magnet is placed underneath a piece of paper. Iron filings are sprinkled on top. The filings arrange themselves in a pattern. What can the student conclude?
A. The paper has become magnetic.
B. A magnetic field extends through the space around the magnet.
C. The iron filings are producing electricity.
D. The magnet has stopped producing a force.
B, a magnetic field extends through the space around the magnet
A student disconnects the battery from the wire wrapped around the nail. What would most likely happen?
A. The nail would become permanently stronger.
B. The electric current would continue forever.
C. The magnetic effect would decrease or disappear.
D. The nail would produce electricity.
C, the magnetic effect would decrease or disappear
A wind turbine is turning because of moving air. The turbine is connected to a generator. What is the ultimate purpose of the generator?
A. To turn electricity into wind
B. To convert mechanical energy into electrical energy
C. To store magnetic fields
D. To convert electricity into sunlight
B, to convert mechanical energy into electrical energy
Which of the following is NOT part of the electromagnetic spectrum?
A. Visible light
B. X-rays
C. Sound waves
D. Microwaves
C, sound waves
Which situation describes an electric current rather than static electricity?
A. Electrons accumulate on a balloon.
B. A balloon sticks to a wall.
C. Electrons steadily flow through a wire.
D. Hair stands up after rubbing a balloon.
C, electrons steadily flow through a wire
According to the reading, what happens when an electric charge moves?
It creates a magnetic field
Two students build electromagnets using the same type of nail. Student A connects the wire to a battery, while Student B does not connect the battery. Which student's nail should produce a magnetic field?
Student A's nail, because current is flowing through the wire
Imagine a power plant's turbine suddenly stops spinning. Based on the reading, what would most likely happen to the generator's ability to produce electricity?
its ability to generate electricity would decrease or stop because the mechanical motion is needed to generate the electrical current
Electromagnetic waves are made of interacting electric and magnetic fields. How are the electric and magnetic fields oriented relative to each other?
they oscillate perpendicular to each other
A student says, "Static electricity and electric current are completely different forces." Based on the reading, how should this statement be corrected?
Both involve electric charges/electrons; static electricity involves accumulated charge, while electric current involves the steady flow of electrons
A scientist observes that a moving electric charge produces a magnetic field. What does this demonstrate about electricity and magnetism?
They are connected aspects of electromagnetism
Why are electromagnets useful in machines such as motors and generators?
they allow electricity and magnetic fields to interact, producing forces or energy transformations that can make machines work
A wind turbine and a coal-powered turbine may use different energy sources, but they can both produce electricity using a generator. What principle allows this to happen?
electromagnetic induction—the interaction between moving magnets and coils of wire produces electricity
A student notices that Wi-Fi, cell phones, microwave ovens, and visible light all involve electromagnetism. What does this suggest about electromagnetism?
electromagnetism has many practical applications in everyday technology