Unit 14 Lab
Academic Physics
Mr. Helzer
Name___________________ Number___________________
Electromagnetic Devices
During this lab you will explore a number of different electromagnetic devices. These devices
are very expensive. As a result, take extreme care not to damage these devices. Follow the instructions
below for each device.
Caution: These devices rely upon electrical current. Misuse of these devices may result in injury or
death.
Device Number 1: The compass.
1. A compass needle is a _______________________.
2. Bring the bar magnet close to the compass. How does the compass needle behave as the bar magnet
approaches it?
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3. What does this experiment demonstrate about two magnets in close proximity to one another?
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Device Number 2: The Electromagnet
1. The device to the right is an
electromagnet. What does the battery
contribute to the electromagnet?
_____________________________
2. We can treat the __________________ supplied by the battery as ____________ _______________.
3. Moving electrons interact with the magnetic domains found in the iron core of an electromagnet.
Describe this interaction. What is the official name of this interaction?
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4. What type of electrical current does an electromagnet utilize in order to function?
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5. There are compasses at each end and at various positions near the body of the electromagnet.
Describe the alignment of these compasses relative to the electromagnet. Why do these compasses align
in such a fashion?
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6. The demonstration electromagnet is hooked up in such a way as to allow the current to be manually
reversed by switching the position of a three-way switch. Turn the three-way switch on in one direction
and observe the behavior of the compass needles. Next, switch the position of the three-way switch and
observe the behavior of the compass needles. Describe what you observed.
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Device Number 3: The Solenoid
1. Describe the similarities and the differences in an electromagnet and a
solenoid.
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2. The picture to the right is similar to the solenoid experiment set
up in the room. Circle the part of this picture that is the solenoid.
3. What type of electrical current does a solenoid need in order to
function?
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0.0
12.5
0.0
0.285
4. Now place the switch in the on position. Do not hold it in the
on position for very long as the solenoid will overheat causing
damage to the hollow plastic core. Describe what happened when
you turned the switch on.
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5. Touch the solenoid. What do you feel? What is moving through the wire that makes it feel this way?
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Device Number 4: The Transformer
1. The device to the right is a transformer. Essentially, a
transformer utilizes two _________________________
in order to accomplish its purpose.
2. What is the primary purpose of a transformer?
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3. Label the primary and secondary sides of the transformer in the picture above. Explain why you
labeled the figure in this way.
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4. Flip the switch so that it is in the DC power position. What happened to the light bulb in the figure
above? Describe the interactions between the electrons and the magnetic domains in the metal of the
transformer that resulted in the light bulb behavior you observed.
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5. Flip the switch so that it is in the AC power position. What happened to the light bulb in the figure
above? Describe the interactions between the electrons and the magnetic domains in the metal of the
transformer that resulted in the light bulb behavior you observed.
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6. In order for a transformer to function, what type of electricity does it need? Explain your answer.
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Device Number 5: The DC Electric Motor
1. DC Electric Motor Anatomy. There are four stickers on various locations on the model DC electric
motor. Identify the number on the sticker that corresponds to parts listed below
Part
Sticker Number
Permanent Electromagnet Field Magnet
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Armature (Rotor)
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Brushes
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Commutator
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2. Label the parts listed in number one on the figure above.
3. The DC electric motor uses a DC power supply; however, the rotors must periodically change poles
in order for the motor to work. Which of parts listed in number one above aid in making this switch?
What type of current actually flows through the armature? How do these two parts accomplish this
switch?
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4. Move the switch to the on position and observe the DC Electric Motor in operation.
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