Wireless Charging in Smartphones

Battery has been the most crucial part in smartphones for all of us. Smartphone batteries have gone through some decent improvements in the past couple of years. The very first battery type which was used in cellphones was the ‘Nickel-Cadmium‘ battery. After that, came the most popular ‘Lithium-ion‘ batteries that totally proved to be game-changing in the smartphone industry. Now, let’s keep the batteries aside for a minute and focus on how they are ‘recharged’.

Inside a smartphone

One way is to simply plug your charger in the power outlet and charge your smartphone by a USB cable. Another way is to ‘wirelessly‘ charge your smartphone (although it’s not completely wireless, haha). But wait, how can electricity be transferred wirelessly? Well, this is possible thanks to ‘electromagnetism‘.

Electromagnetism was first discovered by Oersted in 1820. He accidently came to know about fascinating relationship between electricity and magnetism. He discovered that electric current flowing through a conductor(copper wire) generates a magnetic field around it. This proved that electricity and magnetism go hand in hand.

In 1831, Michael Faraday, discovered a phenomenon known as ‘Electromagnetic Induction‘. This is the principle on which the concept of wireless charging in smartphones is based.

Electromagnetic Induction

Consider two circular coils of conducting copper wire. In one of the coils, an electric current is being passed through the coil while in the other coil, no current is passed. These two coils are placed side by side.

Now as Oersted saw that a magnetic field is generated when electric current is passed through a conductor, in this case also, a magnetic field will be generated by the circular copper coil through which an electric current is passed. Michael Faraday discovered that if we create an oscillating magnetic field (magnetic field that changes), then that changing magnetic field can induce an electric current in the second coil. An electric current will be generated in the second copper coil without any contact with the first coil through which an electric current is being passed. This phenomenon is known as ‘Electromagnetic Induction’.

Thus, it was proved that electricity and magnetism are related to each other and occur simultaneously. And thus, a new branch of physics, Electromagnetism, came into existence.

How Does Wireless Charging Work?

Wireless charging in smartphones takes the advantage of ‘electromagnetic induction’. In a wireless charger, there’s a conducting coil through which an electric current is passed. This coil acts as a transmitter.

There’s another conducting coil at the rear(back) side of the smartphone. The magnetic field generated by the coil placed inside the charger induces an electric current in the coil placed inside the smartphone. This induced electric current is then used to charge the battery of the smartphone.

And that’s the working of a wireless charger. It’s simple science.

But, wireless charging has some disadvantages. Firstly, it can be slow as compared to traditional charging. Remember that in this process, heat is also generated and thus, it can make your smartphone temperature a little bit high. Wireless charging is only possible if the back of the smartphone is made up of plastic or glass. If the smartphone has a metal body, wireless charging won’t work.

That’s all for now. Signing off.

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