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Physics Unit Activity Unit 5: Magnetism
This Unit Activity will help you meet these educational goals:
● Science Inquiry—You will make observations from real-world video, analyze your
results, and write explanations. You will also conduct online research, in which you
will collect information, write explanations, and trace connections between ideas.
● STEM— You will apply mathematical and scientific tools and knowledge to analyze
real-world situations. You will also enlarge your understanding of science as a
creative human activity.
● 21st Century Skills—You will employ online tools for research and analysis and use
critical thinking and problem-solving skills. You will also apply creativity and
innovation to communicate knowledge effectively. Introduction
As you know, the story of magnetism began thousands of years ago, but it wasn’t until the
nineteenth century that scientists understood that electric currents produce magnetic fields.
Many important scientists contributed to the field of magnetism, in particular, Michael
Faraday. In this activity, you will watch a video and closely observe some of the behaviors
these scientists discovered back in the day. You will also create a timeline connecting these
scientists, then explain how the audio speaker—a common and useful piece of modern
technology—operates by applying the laws relating electricity and magnetism.
__________________________________________________________________________ Directions and Analysis
Task 1: Faraday’s Law
In this video set, a coil of wire is connected to a galvanometer (voltmeter) and a magnet is
moved near the coil.
In this activity, you’ll examine this movement and compare different videos with each other.
Next, you’ll state some generalized rules about the motion of a magnet near a wire coil,
illustrating those rules with specific videos.
a. To begin your investigation, open this Web page related to Faraday’s law, and then watch
the videos listed in the table below. These are most—but not all—of the videos available
on the Web page. As you watch each video, take notes on what you observe, both
regarding the specific action you see and what happens to the voltage during the motion.
You may need to replay some of the videos more than once. You also might find it useful
to write your observations as they compare to a video you’ve previously watched. This will
reduce the amount of detail you need to include. It will also help you make comparisons
for your analysis in part (b) below.
1 Type your responses in the table: Video Observations (Action and Result) north-left-1 north-left-3 no-motion perpendicular north-right north-rightoutside
south-right-2 through-1 through-3 through-4 b. After watching all of the videos, write down at least three ways in which the movement of
a bar magnet can vary to change how the voltage is generated. For each statement,
provide a pair of contrasting videos as examples to illustrate your point. Finally, as part of
each statement, explain the “why” behind each variation.
2 Type your response here: Task 2: Loudspeakers
As you know, loudspeakers are used for communication at sporting events, and in schools or
supermarkets. Research loudspeakers on the Web. Describe the components of a speaker
and explain how it produces sound. In particular, explain how the force on a current-carrying
wire in a magnetic field is used to make a speaker operate.
Type your response here:
In order to translate an electrical signal into an audible sound, speakers contain
an electromagnet: a metal coil which creates a magnetic field when an electric
current flows through it. This coil behaves much like a normal (permanent)
magnet, with one particularly handy property: reversing the direction of the
current in the coil flips the poles of the magnet. Inside a speaker, an
electromagnet is placed in front of a permanent magnet. The permanent magnet
is fixed firmly into position whereas the electromagnet is mobile. As pulses of
electricity pass through the coil of the electromagnet, the direction of its
magnetic field is rapidly changed. This means that it is in turn attracted to and
repelled from the permanent magnet, vibrating back and forth. The
electromagnet is attached to a cone made of a flexible material such as paper or
plastic which amplifies these vibrations, pumping sound waves into the
surrounding air and towards your ears.
Task 3: Timeline
Throughout this lesson, you learned about the lives and contributions of key scientists in this
area of physics. Create a timeline that ties them all together. The timeline does not need to be
highly detailed, but it should do the following:
Include at least the four major scientists covered in this unit: Oersted, Ampère, Faraday,
and Tesla.
● Include key contributions of each scientist and provide a year, if possible, for those
contributions.
● Note any relationships among these and other scientists, especially if one developed
something based on the work of another.
● Arrange the scientists chronologically by their first key contribution, not by their birth date.
● Type your response here: __________________________________________________________________________
3 Evaluation
This project will be evaluated on a rubric that is based on the completeness, clarity, and
thinking you exhibit in the Directions and Analysis section above.
Points possible: 10
● Faraday’s Law: 6 points maximum ● Loudspeakers: 2 points maximum ● Timeline: 2 points maximum Faraday’s Law - 6 points Loudspeakers - 2 points accurate, detailed video observations (3
points) explanation of how a loudspeaker works
from an electromagnetic perspective (2
points) analysis – motion variables (3 points)
Timeline - 2 points
timeline relating the scientific contributions of
Oersted, Ampère, Faraday, and Tesla 4
Attachments: