Introduction to electromagnetic Induction

Electromagnetic induction is a medium or means of sending information/signals/power wirelessly by means of electric current vibrating in phase with magnetic fields.

Electromagnetic induction is use for transferring electric current wirelessly without the need of wires or conductors.

In other words Wireless Power transfer (WPT), wireless power transmission, wireless energy transmission (WET), or electromagnetic power transfer is the transmission of electrical energy without wires as a physical link. 

In a wireless power transmission system, a transmitter device, driven by electric power from a power source, generates a time-varying electromagnetic field, which transmits power across space to a receiver device, which extracts power from the field and supplies it to an electrical load. The technology of wireless power transmission can eliminate the use of the wires and batteries, thus increasing the mobility, convenience, and safety of an electronic device for all users.

Wireless power transfer is useful to power electrical devices where interconnecting wires are inconvenient, hazardous, or are not possible.

How do power transfer by electromagnetic induction works?

First as a beginner, when a coil of copper wire is wound around  an iron rod, and a battery is connected to it, as we know, batteries produce direct current (DC), the iron becomes a magnet. When the battery is disconnected it looses it magnetism and then becomes a normal metal.

This is known as a temporary magnet, which is mostly refered to as electromagnet.

The iron becomes a magnet because of the flow of electrons through the coil. When current flows through a coil of wire, magnetic field is produce around it,and it's stable. i.e it has a fixed North and South pole.

Electrons flowing through a coil of wire creates magnetic field.

Also, when an high frequency alternating current of about 40Hz is passed a coil of wire, it produces a varying magnetic field. i.e it's magnetic field changes over time from North to South and South to North. This type of field produced is called an electromagnetic field.

When a coil of wire of certain number of turns is connected to an alternating current of high frequency, and another coil with the same number of turns and size is placed near it magnetic field, email current is induced into the coil, because the electromagnetic field produced by the first coil makes the electrons move back and forth, thus inducing current into it. 

When using electromagnetic induction as a means of transferring power, there are basically two parts.

1. Transmitter.
2. Receiver.

1. Transmiter.

This is use for transferring signals or electric current from a source to a receiver. It do consists of turns of wire with more than 15 turns depending on it application. And it consists of an oscilating circuit which supply an alternating current of certain frequency.  Mostly some transmitter's oscilating circuits get their input power from DC, for example a battery. They convert a low voltage DC into an high voltage AC which is then made to flow through the transmitter coil.

2.Reciever.

This is use to receive the electromagnetic field produced from the transmmiter coil. The reciever coil is usually in the same size and number of turns with it transmitter.

The reciever is made up of coils of wire, a rectifier and sometimes a boost converter (for stepping up voltage).

When are receiver coil is placed in the electromagnetic field of the transmitter, electric current is induced into it and then rectified by means of diodes. Depending on the design it can then be stepped up by a boost converter.

Simply, electromagnetic power transfer, is are transmission of electric power wirelessly by means of electromagnetic wave.

First of all the electric power is converted into an high frequency, high voltage by means of oscilators and then converted into electromagnetic power it flows through a wire. The electromagnetic power can travel through vaccum, obstacles, liquids and many other materials without obstruction, it is then converted back into electricity by the reciever.

In the 1890s Nikola Tesla, Serbian American demonstrated that electricity can be transferred wirelessly without the need of wires by using electromagnetic induction.

He was the first to develop the wireless power system which he used to transmit energy over a very long distance by resonant coupling.