Certain smartphones these days offer the useful function of wireless charging. For some people, this feature is essential, others think it’s pointless. One question remains unanswered though: how is it possible to transfer energy without a cable?
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Fast charging and electromagnetic induction
To fully understand how wireless charging works, you need to understand the concept of an electromagnetic field and, more generally, electromagnetic induction, which you may already be familiar with if you have an induction cooker in your kitchen. What is the link between an induction cooker and a smartphone, you ask? Electromagnetic induction is an energy transfer system, meaning that it can be stored (as in the case of the smartphone) or used.
So how does this energy get transferred? Well it’s a question of forces. Imagine two people holding opposite ends of a rope: if one person decides to make waves with the rope, the other person will receive the waves as they travel down the rope. This is a very generalized way of explaining electromagnetic induction: a force sends energy from one point to another. The base unit (powered by electricity) transmits energy to the smartphone via electromagnetic fields. The sensors on the smartphone recover the energy and channel it to the battery for storage.
Electromagnetic induction charging only works over very short distances. © ANDROIDPIT
How is the charging speed calculated?
Again, it’s all about the forces. As the energy is transmitted through electromagnetic fields, the speed depends on these fields. The bigger they are, the faster it will be. The problem is the fields are pretty small because the smartphone (because of the material (metal etc.) it’s