Issue 400 What is a Tesla Coil? August 13, 2014

Nikola Tesla was a competitor to Thomas Alva Edison and won. Tesla invented light bulbs, and other inventions that would leave their mark on history and would have his Alternating Current surpass Edison's Direct Current electricity. One of these many inventions was the Tesla coil, a magnificent device that could generate and send electricity through the air.  So what exactly is it?

A Tesla coil:  This device is a type of transformer for electricity.  The idea was to send electricity through the air to power electrical devices.  So here is how it works complements of: www.realclearscience.com (web address to article:  http://www.realclearscience.com/articles/2014/01/29/how_tesla_coils_work_108474.html )

"The power of the Tesla coil lies in a process called electromagnetic induction, i.e., a changing magnetic field creates an electric potential that compels current to flow. Conversely, flowing electric current generates a magnetic field. When electricity flows through a wound up coil of wire, it generates a magnetic field that fills the area around the coil in a particular pattern, shown with lines below:

Photo modified from Los Alamos National Lab.

Similarly, if a magnetic field flows through the center of a coiled wire, a voltage is generated in the wire, which causes an electrical current to flow."

"The electric potential (“hill”) generated in a coil of wire by a magnetic field through its center increases with the number of turns of wire. A changing magnetic field within a coil of 50 turns will generate ten times the voltage of a coil of just five turns. (However, less current can actually flow through the higher potential, to conserve energy.)"

"The Tesla coil requires ......... a capacitor to store charge and fire it all in one huge spark. The circuit of the coil contains a capacitor and a small hole called a spark gap. When the coil is turned on, electricity flows through the circuit and fills the capacitor with electrons, like a battery. This charge creates its own electric potential in the circuit, which tries to bridge across the spark gap. This can only happen when a very large amount of charge has built up in the capacitor.

Eventually so much charge has accumulated that it breaks down the electrical neutrality of the air in the middle of the spark gap. The circuit closes for a fleeting second and a huge amount of current blasts out of the capacitor and through the coils. This produces a very strong magnetic field in the primary coil.

The secondary wire coil uses electromagnetic induction to convert this magnetic field to an electric potential so high that it can easily break apart the air molecules at its ends and push their electrons in wild arcs, producing enormous purple sparks. The dome on the top of the device acts to make the secondary coil of wires receive energy more fully from the first coil. With some careful mathematical calculations, the amount of electrical energy transferred can be maximized."

Conclusion:  This is how it works in the most basic of ways.  We use systems based on this for Tesla's alternating current in our transformers outside our homes.  Though they are not sending it through the air in this case, just converting electricity to a more manageable level for our homes.  But Tesla's Coils are now being used as wireless chargers for phones and is predicted to eventually replace all electrical wiring in the home at some point in time when it is deemed cost effective to be in the home.  So Tesla, thank you for your hard work.