The Wonders of:

Electromagnetic Induction

By CJ Cruz and Grace Nam

What is Electromagnetic Induction?

First of all, electromagnetic induction can be defined as the process in which a circuit's electrical current is generated by being near to another circuit that has an alternating current flowing through it. Generators and motors both use this principle. The devices are fairly similar and they both have the same basic structure. Both are comprised of a system in which there is a magnet, which generates a magnetic field, surrounded by metal coils. In a generator, the coils around the generator are spun thus creating an electric force. The opposite occurs in motors; an electrical current is passed through the coil in order to make the coil itself spin. In essence, generators convert mechanical energy into electrical energy while motors convert electrical energy into mechanical energy. These are the whole concepts of electromagnetism; the conversion of a magnetic force into an electric force and vice versa.


How Has Electromagnetism Improved Our Lives?

The Mechanical Flashlight:

Although it may not seem that important, devices such as these hold the key o energy in the future. This particular flashlight is a mechanical "Faraday" flashlight, which means that it has a nearly unlimited supply of clean energy (as long as it is shaken). An electrical force is created from changes in the magnetic field within the flashlight (the structure is similar to that of an electromagnet where the coil produces its own magnetic field after the initial induction). Within the flashlight is a metal coil which is embedded from one end to the other end. There is a freely movable magnet inside the tube which allows a current to be generated. When the flashlight is shaken, the movement of the magnet (and therefore its change in magnetic force) changes the magnetic flux within the coils and produces an electric field Although this is minor, it shows how clean and renewable sources of energy are possible, we just need to refine them to make them more practical.
Dynamic Speaker Systems:

Music is great! Nearly every person enjoys music because its one of the only forms of entertainment that can be enjoyed in almost any situation imaginable. Speakers make life better for music enthusiasts because they allow for music, or other audio inputs, to be played at much louder volumes than what is normally possible. Dynamic speakers have a thin, flexible diaphragm at the surface (this is the part on large speakers that vibrates a lot). The diaphragm is connected to a metal coil that is wrapped around a magnet. When incoming audio signals arrive (in the form of various electrical impulses), they flow through the coil. This current causes the coil to vibrate (in patterns specific to the impulses) due to the relationship between the current and the magnet's magnetic field. When the coil vibrates, it causes the diaphragm to vibrate as well. These vibrations then produce audible and loud sound waves that sound like music!

Car Battery Generators:

Although previously covered in how generators work, it has yet to be discussed how these devices have made life so much better. Well this is how, if you go somewhere to experience the wilderness (or if you go to a Walmart) and when you want to leave your battery dies, this device can keep you from getting stranded. Although the generator does require a small amount of effort to provide a large enough jolt to the car's battery, it saves time and energy. Nobody would have to be called to jump your car and you wouldn't have to approach random people (if you were in the Walmart parking lot) asking them to help you in this dire situation. Instead, you could mind your own business and get on your way in just a few minutes!

Washing Machine:

In a washing machine the power is created by a moving turbine attached to a generator. The turbine spins by using fuel which then provides the mechanical energy for the generator to run. This causes electromagnetic induction to occur because the when the turbine spins, a current is introduced to the system and a voltage is created. This voltage allows our washing machines to spin and our clothes to come out clean! :)



Acoustic/Electric Guitar:

An acoustic or electric guitar is just a guitar that uses acoustic sounds that can be amplified. The guitar's sound can be amplified through electromagnetic induction through the use of a pickup. The pickup in the guitar uses electromagnetic induction to convert the guitar's vibrations into an electrical current. This electrical current can then be amplified through the pickup transferred into an amp where the currents are reinterpreted as sounds (similar to the dynamic speaker method) which makes the guitar louder.

Works Cited:

"Applications of Electromagnetic Induction." Applications of Electromagnetic Induction. N.p., 22 July 1999. Web. 03 May 2013. <http://physics.bu.edu/~duffy/py106/Electricgenerators.html>.


Gerbis, Nicholas. "How Induction Cooktops Work." HowStuffWorks. HowStuffWorks, n.d. Web. 03 May 2013. <http://home.howstuffworks.com/induction-cooktops2.htm>.


"Dynamic Microphones." Dynamic Microphones. MediaCollege, n.d. Web. 03 May 2013. <http://www.mediacollege.com/audio/microphones/dynamic.html>.


"How Faraday Flashlights Work." How Faraday Flashlights Work. Shake-Flashlights, n.d. Web. 03 May 2013. <http://www.shake-flashlights.com/how-they-work.html>.


"Patent US6486582 - Dynamo-electric Machine Rotating by Electromagnetic Induction Such as It ... - Google Patents." Google Books. IFI Claims Patent Services, n.d. Web. 03 May 2013. <http://www.google.com/patents/US6486582>.


Russell, Daniel A. "Physics of Guitar Pickups." Physics of Guitar Pickups. N.p., n.d. Web. 03 May 2013. <http://www.acs.psu.edu/drussell/guitars/pickups.html>.


Photo Credits:

Washing Machine: Grace Nam

Engine: CJ Cruz

Generator: CJ Cruz

Speaker: CJ Cruz

Flashlight: CJ Cruz

Guitar: Grace Nam