Content Benchmark P.8.B.2
Students know electric currents can produce magnetic forces and magnets can cause electric
currents.
1st Item Specification: Understand the relationship between electric currents and magnetic
forces.
Depth Of Knowledge Level 1
1. For a magnet to induce an electrical current in a stationary coil of wire, the magnetic field
must be
A. static.
B. changing.
C. strong.
D. weak.
2. Which of the following will be surrounded by a magnetic field?
A. A wire that is conducting an electrical current.
B. An aluminum rod that has been touched by a magnet.
C. Two copper wires held close together.
D. A pot being heated on an electric stove.
3. Which of the following will increase the strength of the magnetic field in an electromagnet?
A. Decreasing the current in the wire that surrounds the iron core.
B. Removing the iron core from the center of the electromagnet.
C. Decreasing the number of loops of wire around the iron core.
D. Increasing the number of loops of wire around the iron core.
4. The diagram below is of a solenoid, which is a type of electromagnet used to make on-off
switches. Use this diagram to answer the next question.
B. Battery
C. Coil of Wire
A.
(From: http://www.school-for-champions.com/science/electromagnetism.htm)
What part of the electromagnet is identified by the letter A in the diagram above?
A.
B.
C.
D.
The magnetic field.
The electrical current.
The core of the electromagnet.
The source of electrical current.
Depth Of Knowledge Level 2
5. Which of the following is NOT true about the relationship between electricity and
magnetism?
A. Generators use magnets to induce an electrical current.
B. Motors use electrical currents to create a magnetic field.
C. A magnetic field can be used to induce an electrical current.
D. All magnets are surrounded by an electrical field.
6. Use the diagram below to answer the next question.
From: http://www.school-for-champions.com/science/electromagnetic_devices.htm
Moving the magnet back and forth through the coil of wire will cause which of the
following to occur?
A. Electrical current will flow through the magnet.
B. Electrical current will flow through the wire.
C. The magnet will become stronger.
D. The magnet will lose its magnetic field.
7. Sean and Shanika conducted an investigation to compare the number of turns of wire
around the iron nail in an electromagnet, to the number of paper clips the electromagnet
could pick up. Their data appears on the graph below
The number of turns of wire on an
electromagnet vs. the number of paper
clips picked up.
Number of paper
clips picked up
10
8
6
4
2
0
0
5
10
15
20
25
Number of turns of wire
How does decreasing the number of turns in the coil of wire affect the strength of the
magnetic field of the electromagnet?
A. The magnetic field does not change.
B. The magnetic field becomes stronger.
C. The magnetic field becomes weaker.
D. The magnetic field disappears.
8. Which of the following devices work because an electric current is used to create a
magnetic field?
A. A generator and a windmill.
B. A generator and an electric motor.
C. A bar magnet and a battery.
D. An electric fan and a vacuum cleaner.
Constructed Responses P.8.B.2
9. Use the following diagram to answer the question below.
Wire wrapped
around an iron
nail.
Wire
Battery
Switch
(From: http://www.energyquest.ca.gov/projects/electromagnet.html)
When the switch is closed, an electromagnet will be formed.
A. Circle the electromagnet in the picture?
B. Explain what an electromagnet is.
C. Why must the switch be closed in order for the electromagnet to work?
10. Use following picture of an electromagnet made from an iron nail wrapped with coils of wire
to answer the following question.
http://www.school-for-champions.com/science/electromagnetism.htm
The more turns of wire there are around the soft core of iron, the more paper clips the
electromagnet will pick up. Observe the data on the table and answer the question below.
Number of turns
Number of paper clips
in the coil of wire
picked up by the
of an electromagnet. electromagnet.
5
2
10
4
15
8
20
10
A. Construct a line graph comparing the number of turns of wire on the electromagnet to
the number of paper clips it can pick up.
B. Explain why the electromagnet picks up more nails as the number of coils increases.
Content Benchmark P.8.B.2
Students know electric currents can produce magnetic forces and magnets can cause electric
currents.
Answers to Sample Test Questions
1.
2.
3.
4.
5.
6.
7.
8.
B, DOK level1
A, DOK level 1
D, DOK level 1
A, DOK level 1
D, DOK level 2
B, DOK level 2
C, DOK level 2
D, DOK level 2
Constructed Response 3-point Answers and Score Rubrics:
Constructed Response #1
Response addresses all parts of the question clearly and correctly.
An electromagnet is formed when electricity creates a magnetic field
around a metal like iron that can be magnetized. Closing the switch
allows the electricity to flow. When the electricity flows the
electromagnet will work.
3 points
Student answers must include three the following: (a) The wirewrapped nail is the electromagnet. (b) An electromagnet is a magnet
created by an electrical field. (c) Electricity will not flow if the switch
is not closed. (d) Electricity is needed to make the nail
magnetic/create the magnetic field.
Response addresses all parts of the question.
Student answers include only two of the following:
 The wire-wrapped nail is the electromagnet.
2 points
 An electromagnet is a magnet created by an electrical field.
 Electricity will not flow if the switch is not closed.
 Electricity is needed to make the nail magnetic/create the magnetic
field.
Response does not address all parts of the question.
Student answers include only one of the following:
 The wire-wrapped nail is the electromagnet.
 An electromagnet is a magnet created by an electrical field.
1 point
 Electricity will not flow if the switch is not closed.
 Electricity is needed to make the nail magnetic/create the magnetic
field.
0 point
Response is totally incorrect or no response provided.
Electricity or magnetism listed without explanation. Not answered or
off-task.
Constructed Response #2
The number of turns of wire on an
electromagnet vs. the number of paper
clips picked up.
Number of paper
clips picked up
10
8
6
4
2
0
0
5
10
15
20
25
Number of turns of wire
3 points
Response addresses all parts of the question clearly and correctly.
The electromagnet picks up more paper clips when there are more
turns of wire around the nail because the magnetic field becomes
stronger. Student answers must include the following. (a) A line
showing the directly proportional relationship between the number of
turns of wire and the number of paper clips picked up. (The graph
must be a line, not bars). (b) Data points on the line representing the
number of turns of wire and the number of paper clips picked up.
(Bars acceptable if they are accurately placed). (c) Explanation that
more turns of wire will cause the magnetic field (magnetism) to be
stronger. (d) Correct labels for both x-axis and y-axis.
2 points
Response addresses all parts of the question and includes only minor
errors.
1 point
Response does not address all parts of the question.
0 points
Response is totally incorrect or no response provided.