# Photo Essay

## Electromagnetic Induction, Generators and Motors, Oh My!

Electromagnetic Induction is properly defined as the production of potential difference, or voltage, across a conductor when exposed to a magnetic field. The basic law of electromagnetism predicts how a magnetic field will respond to an electrical current and and electrical force. This was the law created by Michael Faraday who is credited with the discovery of Electromagnetic Induction.

Electromagnetism plays a major role in the productivity of generators and motors.

Generators are run through the conversion of mechanical energy into electrical energy. The movement of this energy creates voltage between the electrical conductor, which turns the electric charges thus producing an electrical current, which is the basic understanding of Faraday's discover of electromagnetic induction.

Motors work through an electrical current flowing through a magnetic field creating a force. The force causes the coil to turn producing torque and electrical force. Motors seem to work similar to the generator in the relation to electromagnetic induction.

Electromagnetism has also had a large affect on our everyday lives. Here are five of some of the ways electromagnetic has helped us.

1) They help us detect help problems that might be occurring in our body. (MRI's)

2) The ability for easy transportation from place to place. (Trains)

3) The storage of a computer file or item that can be easily transported and presented in another location. (Flash-drive)

4) The security of important items or money for future occasions. (Bank Safe Doors)

5) The easy communication device that allow us to talk to others that spanned a far distance. (Telephone, Cellphone)

## Speaker

A speaker uses a variety of magnets to help it produces sound waves. Speakers are composed of a voice coil, a magnet, wires leading to the stereo, and a device used to produce vibrations. As long as there is motion between the magnet and a wire there will be an induced current. This current uses a magnet force which pushes along the wire and produces an electrical force. This electrical force causes the production of vibrations, which help to create the sound waves coming out of the speakers.

Speakers do not only have to be used for listen to music. Police are able to the benefits of electromagnets of speakers to broadcast information to people in need of help. They can provide information to far distances and help people protect others. For example, speakers are used to produce a warning sign for people out in the plains that a tornado is coming or there is a warning.

## Magnet on a Refrigerator

The magnet on the refrigerator can hold many different things from school work you did well on, to you to do list for the week. The magnet can hold messages that need to be conveyed to someone that may not be there at the time.

The front of the refrigerator is noramlly a large magnet that you can attach other magnets to. This magnet is made by placing a piece of iron or steel in a strong magnetic force. The magnet being placed on the door causes the rearranging of the atoms on the door to allow for the magnet to "stick" to the door through the opposite poles of the two magnets.

Although it does not use a motor or generator the magnet on the refrigerator can be a helpful tool to get messages across to your family, helping to improve our lives.

## Compass

A compass can be a very helpful device when you are stuck somewhere and don't know which way to go. Normally in a there is a magnetized needle which is allowed to spin freely and point in the four main cardinal directions, North, South, East and West. Magnet is located at the end of one side of the needle and will align with the natural magnetic field of the Earth. the composition of the Earth's magnetic field is such that the south is at the top and the north at the bottom. This allows for the "opposites to attract" with the needle magnet north side to attract to the south and point northward.

Compasses are useful instruments in today's world. They can be used for navigation of the seas for ocean liners and planes traveling all over the world. The compass allows us to be pointed in the right direction, which will always be north.

## Telephone

Electromagnetism induction is displayed in modern technologies such as telephones. In telephones, electromagnetic induction is carried throughout the mouth piece where people communicate from.

In the ear piece there is an iron core, diaphragm, and a permanent magnet. A speaker sets the air into oscillating motion. The mouth piece converts the sound into an electric current. Then as you speak to someone on the phone, the current is transferred to the person on the other line. As the iron core is magnetized, the current passes through the solenoid. The magnetic field’s current strength changes along with the current. As the current becomes stronger, the magnetic field gets stronger. That works both ways so as the current becomes weaker, the magnetic field gets weaker. The diaphragm vibrates at the frequency of the changeable current. The process turns the electrical currents into sound.

## Microwave Ovens

Microwave ovens are among the many devices we use today that contain electromagnetic radiation. The microwaves are electromagnetic waves which are oscillations of the electric field and magnetic field. The fields lie perpendicular to each other constantly between positive and negative. For microwaves ovens, to heat the food, they contain microwaves that oscillate at a frequency of 2.45 gigahertz. The heating works by heating the water in all the foods. The microwave energy in turned into heat energy of water molecules which makes the other molecules in the food heat up also. Charges create their own electric field that exerts its pressure on other particles. Electromagnetic waves as microwaves produce constantly changing electric fields. Thus, the water molecules react to the changing electric fields.

## Credit Card

On all credit cards, there is a magnetic stripe on the back often called a magstripe. This magstripe is made up of very small magnets particles that are iron-based. Each particle is a miniscule bar magnet. The magstripe has the small bar magnets, which can be magnetized in either the South or North Pole direction in order for people to write on them. When the credit card is swiped through machines, the movement of magnetized areas causes small voltages which read the data on the card. If the strip on the card becomes demagnetized it will not work in credit card machines. The reason you have to swipe the credit card quickly is because magnetic machine can damage the small magnetic particles on the magnetic strip which can lead to changing over the North and South Pole.

## Sources

Lopez, Polo. "Soccer." : Speakers and Electromagnetic Induction. N.p., 28 Apr. 2012. Web. 02 May 2013. <http://polo-soccer.blogspot.com/2012/04/speakers-and-electromagnetic-induction.html>.

Starr, Gigi. "How Does a Refrigerator Magnet Work?" EHow. Demand Media, 27 Jan. 2009. Web. 02 May 2013. <http://www.ehow.com/how-does_4739775_refrigerator-magnet-work.html>.

"Compass." Parts. Compass Dude, n.d. Web. 02 May 2013. <http://www.compassdude.com/compass-description.shtml>.

"What Is Electromagnetism." What Is Electromagnetism. N.p., n.d. Web. 02 May 2013. <http://www.joeruff.com/artruff/physics/Student_Pages/Electromagnetism/Whatiselectromagnetism.htm>.

"Electromagnetic Induction." Wikipedia. Wikimedia Foundation, 29 Apr. 2013. Web. 02 May 2013. <http://en.wikipedia.org/wiki/Electromagnetic_induction>.

"How Does a Generator Create Electricity?How Generators Work." Industrial Diesel Generators: New & Used Generator Sets â We Buy/Sell. N.p., n.d. Web. 02 May 2013. <http://www.dieselserviceandsupply.com/How_Generators_Work.aspx>

"SPM Physics Form 5 - Electromagnetism: Uses of Electromagnet - Electric Bell." SPM Physics Form 5 - Electromagnetism: Uses of Electromagnet - Electric Bell. N.p., n.d. Web. 03 May 2013. http://physics503.one-school.net/2008/06/uses-of-electromagnet-electric-bell.html