Commonly seen wireless charging, using the "current magnetic effect" and "electromagnetic induction" principle.

In 1819, Danish scientist erst observed that if an electric current was applied to a wire, a magnetic field would be created around it, which would deflect the needle.

Later generations further discovered that the magnetic field generated by wrapping the wire in a ring or even a coil would be stronger and more concentrated, which is called the current magnetic effect.

As for electromagnetic induction, it was discovered by Faraday in 1831.

When a magnet or other source of magnetic field is placed near a coil with no current, the "induced current" on the coil is called "electromagnetic induction".

It is important to note that electromagnetic induction works only if the field "changes", such as the magnet getting closer (and farther away).

If the external magnetic field remains constant, there will be no induced current.

In a word, the current magnetic effect is that the flow of current creates a magnetic field around it, and electromagnetic induction is a constantly changing external magnetic field that causes the coil to generate an induced current.

The combination of these two physical phenomena allows wireless charging.

Current wireless charging devices contain a "charging socket" that is actually a coil.

After connecting the charging socket to the household plug, a magnetic field will be generated around the coil due to the magnetic effect of current.

The electronic products to be charged also have a coil inside. When it is close to the charging base, the magnetic field of the charging base will be induced by electromagnetic induction to generate current on the coil of the electronic products.

The induction current guides the battery to complete the wireless charging between the charging socket and the electronic products.

You might ask, doesn't a magnetic field have to change to have electromagnetic induction?

However, the distance between the charging base and the charging object remains the same, so why electromagnetic induction?

It turns out that the electricity flowing out of the household socket is "alternating current", which means that the direction of the current changes continuously, while following the flow, while reversing the flow.

Because of this, the magnetic field generated by the charging base coil is constantly changing direction, not remaining constant, in accordance with electromagnetic induction conditions.

More and more smartphones and tablets have recently started to offer wireless charging, but unfortunately, when they are charged, as long as the distance from the charging base is a little bit more, the charging efficiency will be significantly reduced.

Even with the latest technology, the charging distance cannot be more than 5 cm. In fact, most mobile devices that can be charged wirelessly at present can only be carried out by completely lying flat on the charging base, which is still a little different from the imagined wireless charging when you walk.