Tesla coil

Have you imagined the power transmission without wires? Most of us don’t. But there was an absolute genius scientist that made a foundation for this invention. He was Nikola Tesla. Tesla created the first model to transmit power from one place to another place without using wires similar to radio signals. Nowadays we are using wireless charging either in smartphones or tablets. This Tesla model is widely known as the Tesla coil. So, what is the engineering behind this life-changing invention? Let’s find out here.

What is a Tesla coil?

We are well familiar with Nikola Tesla several innovations. In his numerous innovations, Tesla dreamed to transmit electricity all over the world without stringing wires across the globe. The inventor came close to accomplishing this when his crazy and creative experiments with electricity led to his creation of the Tesla coil.

It was the first model that could transmit electricity without using any wire; the Tesla coil was a completely revolutionary invention. In the early days, this technology was being used in radio and telegraphy, but variations of the coil in the Tesla model can also do things that are simply amazing like shoot lightning bolts. Tesla developed the coil in 1891. His model contained two coils. The first one is for power transmission and the second one for reception. These coils were specially designed to handle the high frequency and high voltage for their functioning. The concept behind the coil is simple and makes use of electromagnetic force and resonance.

Inside engineering:

The principles behind the Tesla coil are relatively easy and simple. We know that electrical current is the flow of electrons, while the difference in electric potential or voltage between two places is a kind of force that pushes the electrons (current). In simple terms, the current is like water and voltage is like a hill. A high voltage is a steep hill, down which a stream of electrons can rapidly flow whereas a small voltage is like a nearly flat plain with almost no or slightly water flow.

Tesla coil works on the principle of electromagnetic induction. According to this principle, a changing magnetic field creates a voltage that compels the current to flow. In a turn of the coil, the generated electric current generates another magnetic field. And this process goes on continuously till the power losses completely.  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.

In the same way, this principle also says, if a magnetic field flows through the center of the coiled wire, a voltage is generated in the wire, which causes an electric current to flow. This generated voltage increases with the number of turns of wire. For example, a changing magnetic field within a coil of 100 turns will generate ten times the voltage of a coil of just 10 turns.

A power transformer works on the same principle. Tesla coils also do the same thing but in a different way. Let’s understand this, suppose a premade high voltage iron core transformer to go from 110V wall current to roughly 10,000V. The wire with 10,000V is wrapped into the primary coil. The secondary coil contains thousands of turns of thin wire. This steps up the voltage to 1000,000V. This voltage is so strong that can destroy the iron core. To handle this situation only air is present between primary and secondary coils.

Capacitor - energy storing component

Capacitor – energy storing component

The Tesla coil requires one more component, which is a capacitor. Here, the primary task of the capacitor is to store the charge and fire it all in one huge spark. The circuitry of the coil contains a capacitor and a small hole (known as a spark hole). When the circuit is turned ON, electricity flows through the circuit and fills the capacitor with electronic charges (electrons). These stored charges create their electric potential or voltage in the circuit, which tries to bridge across the spark gap between the primary (transmitter) coil and secondary (receiver) coil. This phenomenon can only happen when a large number of charges have built up inside the capacitor.

Once a much amount of charge has accumulated inside the capacitor then it breaks down the electrical neutrality of the air in the middle of the primary and secondary coil (also known as spark gap). The circuit closes for a fraction of seconds and a huge amount of charges blast out of the capacitor and through the coil. This produces a very strong magnetic field in the primary coil.

On the other side, the secondary coil uses electromagnetic induction to convert this magnetic field to an electric potential. That’s how Tesla coil works. Tesla might not have invented a source of unlimited energy, which was his goal while creating Tesla coil, but his design became the pioneer for many innovations for modern technology.

Normally Tesla model contains both coils in a similar structure to generate a powerful spark in the open atmosphere. The normal application of this model is to perform the arch attack.


While the Tesla coil does not have much practical application anymore but Tesla’s invention completely revolutionized the modern technology for wireless power transmission. On the basis of the Tesla model, many inventions had been made. Today we are using wireless charging frequently in our smartphones or computer tablets, the concept behind wireless charging emerges from Tesla coil only. Many of the other inventions of Nikola Tesla is still serving human society. No one can take the place of that absolute genius person. This was the picture behind the Tesla coil.

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