LAB: Building the Best Electromagnet
Background:
In 1820, Hans Christian Oersted discovered that magnetism can be produced by
moving electric charges. However, the magnetic force induced by a straight
current-carrying wire is generally very weak. One way to increase this force is
to increase the current in the wire, but large currents can be fire hazards. A
safer way to create a strong magnetic field is to wrap the insulated, currentcarrying wire into a coil. This current-carrying coil of wire is called a solenoid.
A strong magnet can be created when a substance that can be easily
magnetized, such as iron, is inserted into the center of a solenoid. When
electricity induces magnetism in this manner, the resulting device created is
called an electromagnet.
Purpose:
 To determine how increasing the number of coils in an electromagnet affects the strength of the
magnetic force created.
 To determine how increasing the current through an insulated wire used in an electromagnet
affects the strength of the magnetic force created.
Materials:
D-cell batteries (3)
Single battery in holder
Dual batteries in holder
Insulated wire (2 m)
(coiled into one small and one large solenoid)
Iron nail (large)
Jumper wires (2)
Paper clips (20)
Procedure:
1. Confirm that the nail is not magnetic by attempting to use it to pick up paper clips.
2. Insert the nail into the thin-wire coil with the least number of turns.
3. Count and record the number of turns of wire in this coil.
4. Connect the wire to the single battery terminals with your jumper wires.
5. Observe and record the number of paper clips you can pick up from a single point on the nail.
CAUTION: you have created a short circuit (wire alone has very little resistance), so the wire will
heat up quickly and the battery cannot supply constant current for very long. Disconnect the
battery as soon as you have determined the relative strength of your electromagnet.
6. Record the total number of paper clips picked up for three trials and find the average.
7. Repeat steps 1-6 with the thin-wire coil with the least number of turns and the dual battery pack.
8. Repeat steps 1-6 with the thin-wire coil with the greatest number of turns and the single battery
pack.
9. Repeat steps 1-6 with the thin-wire coil with the greatest number of turns and the dual battery
pack.
Observations and Data:
Number of coils in small solenoid:________
Trial #
Number of coils in large solenoid:________
Table 1: Number of Paper Clips Picked up by Various Electromagnets
Small # of coils
Small # of coils
Large # of coils
Large # of coils
One Battery
Two Batteries
One Battery
Two Batteries
1
2
3
Table 2: Average Number of Paper Clips Picked Up by Various Electromagnets
One Battery (small current)
Two Batteries (large current)
Small # of Coils
Large # of Coils
Small # of Coils
Large # of Coils
Conclusion:
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What
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Summarize the purpose (What were you testing?)
Summarize procedure (How did you test it?)
State the results (How many paper clips did each pick up? Which configuration was the best,
which was the worst? Does this seem right?)
Three possible sources of error (unavoidable limitations of the lab)
How could be these errors be corrected/fixed?
What other variables could be tested?
to turn in:
Title
Purpose
Hypothesis
Data table(s)
Conclusion