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POLY ENGINEERING3

28 Feb 2011Speaker Project

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POLY ENGINEERING3

Goals

1. To understand how speakers work and how the reverse process of turbines work to generate electricity

2. Apply the engineering design process3. Communicate results

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POLY ENGINEERING3

How Power Plants Work

1) Convert Potential Energy to Mechanical Energy

2) Convert Mechanical Energy to Electrical Energy

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POLY ENGINEERING3

How Speakers Work

1) Convert Electrical Energy to Magnetic Energy

2) Convert Magnetic Energy to Mechanical Energy

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How Speakers Work1) Electrical Energy is inputted by Audio

Device

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How Speakers Work2) Electricity passing through a wire creates a

magnet

- Increase the strength of the magnet by wrapping wire into coils.

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How Speakers Work

3) Electromagnet attracts or repels permanent magnet.

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How Speakers Work

4) One magnet is fixed and the other magnet is attached to a membrane. As electromagnet changes direction, membrane vibrates.

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How Speakers Work5) Vibrating membrane moves air

molecules. Air molecules collide with our ear drums and we hear sound.

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Supplies

1 square foot of cardboard1 neodymium magnet

4 feet of magnet wire

Paper plate

1 piece of construction paper

scissors glue

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Speaker Steps

1. Make electromagnet out of wire• -Slightly wider than magnet• -At least 6 inches of wire before and after coil• -Tightly wound

2. Make suspension system• Must support paper plate and allow it to vibrate

3. Connect coil to the center of the paper plate

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Speaker Steps

4. Connect magnet to cardboard

5. Connect suspension system to paper plate

6. Connect suspension system to cardboard

7. Test the Speaker

8. Redesign if speaker doesn’t work

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POLY ENGINEERING3

Assessment

Work with one partner

– Produce a working speaker that clearly plays music

– Produce a write up that details every step needed to make the speaker. Should be written so that a 3rd grader could make the speaker

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POLY ENGINEERING3

Supplies

• Provided with 1 magnet, 4 ft wire, paper, and cardboard

• Extra Supplies– $1 per magnet– $0.20 for every foot of wire