Paper Earphone

MATERIALS:

· Round magnet (ferrite magnet)

(____cm in diameter)

· Cooper wire

· Cellophane tape (scotch tape)

· Thick paper (__ cm x__ cm)

· Connecting wires with alligator clips

and pin plug (see photos)

(*see below for the options)

· Mobile phone (cassette player, computers or any music player can be use)

PROCEDURE:

テキストボックス: Why can magnet and coil produces sound? The coil with electric current passing through it is an electromagnet. The moment you plug the wire to the mobile phone, an alternating current flows toward the coil creating a magnetic field with negative and positive polar that can be alternate and switch on and off. On the other hand, the round magnet as we know has also had it negative and positive polar which is permanent and cannot be alternate and switch on or off. The two magnets (electromagnet and round magnet) interact with each other. When the negative charge from the coil passes, it was attracted to the positive polar of the permanent magnet but positive charge from the coil is repelled by the positive polar of the permanent magnet. When the alternating current switches the electromagnets polar orientation so does the repulsion and attraction process. This process causes the coil to vibrate back and forth at very fast pace and thus vibrates the air creating a sound waves of a required frequency and this we hear the sound. The paper earphone converts electrical energy into sound energy.

Taking it further

1. Try using stainless steel wire or brass wire. Compare the difference between sound waves produced by them. Which wire makes the earphone louder with the same number of coil winding and thickness of wire?

2. Experiment on how to improve the sound of the earphone. You can change the number of turns of coil, thickness of the wire, strength of the magnet, or even try bigger or smaller diameter of coin or wire. Try as many possible way you can think of in improving quality of the sound.

Paper Earphone

1. Make a coil by winding the copper wire into a A size battery or cap of a PET bottle 15-20 times. Leave about 1 and half inch of wire free at one end and on the other end. Wrap the free end of the wire around the coil. The coil will look as shown in the photo.

2. Fold the paper into half and attach the coil in half portion of the paper using. scotch tape.

3. On the other half of the paper, attached the round magnet using scotch tape. Make sure that it will fit in the coil when the paper is fold.

2. Connect the alligator clips of the connecting wires on the free end of the coil and connect the pin plug to the mobile phone-earphone jack.

5. Fold the paper with round magnet and coil and bring it near to your ear. Play music on your mobile phone or music player. Can you hear the music playing?

Note: If you a connecting wire with alligator clip and pin plug is not available, you can buy a separate connecting wire and a pin plug and connect it by yourself or you can buy a disposable earphone and cut the earplug, remove the plastic coating and connect it to the free end of the coil.

* This experiment is adapted from the experiment learned from Hokkaido Science Center, Sapporo.

テキストボックス: EXPERIMENT LISTS PHYSICS Balancing a Dragonfly Does Air Takes Up Space? Improvised Battery (Option 1) Improvised Battery (Option 2) Improvised Battery (Option 3) Tornado in the Bottle Diver Surface Tension and Air Pressure Aluminum Wrap Railway Light to Sound Magnetic field in 3D Simple Kaleidoscope Art in Polarizer Simple Spectroscope Electrostatic Motor Paper Earphone CHEMISTRY Vegetable/Fruit Charcoal Red Cabbage Extract (Identifying Acidity of a Liquid) Alkalinity of a Liquid Crayon Making Hand Printing using Soap Testing Raindrop Acidity using Red Sweet Potato Powder Magic! (Water doesn’t fall?) BIOLOGY 1. Leaves Puzzle ACTIVITIES Fossil Hunting Gold Sieving Smelting Steel Observing Classes Attending Trainings