I’m getting a set of neodymium magnets, and can’t wait to open them. However I also have a few questions about how some things work. For example, what does it mean that electricity and magnetism are different parts of the same thing, or why do positives attract to negatives and not vice verse, or how does an electromagnetic field aka wireless charger power a phone or heat a stove but not your hand, and lastly, what IS electromagnetism at its fundamentals?
Thx
In: Physics
I will answer for the heating part.
First you should check Maxwell laws. It’s for formula linking E (the voltage) and B (the magnetism)
The one we need here is that a changing B (magnetism) induce a voltage if it go through a loop of conductor (metal). Now if there is voltage and a conductor you get current. And if you have current you are heating the conductor by the famous law : P(heating power)= R (resistor) * I(current) * I.
So if you want to heat something you need a loop of a conductor, your hand isn’t one. With the voltage you could charge a phone or heat a resistor.
Ps : positive and negative are totally interchangeable, it’s just a convention and both attract each other but two positives/two negatives doesn’t attract themselves
Electricity is the flow of electrons from one place to another. When electrons move in a unified direction (as opposed to a random one), it creates a magnetic field that alternates polarity rather quickly.
Magnetic fields occur in static magnets (that is, a magnet that is made of an inert material such as nickel or neodymium) because all of the electrons in the structure of the chemical compound that make up the magnet are going in one singular direction around the protons in the molecules. This causes a magnetic field, and if you take a piece of metal and disrupt an electric field by vibrating the metal, this will cause an electrical current to be generated around the magnet.
These two properties are fundamental to magnets and electricity, and are the basis for technology like speakers and electric guitars (an electric guitar has a steel [and therefore magnetically reactive] string over a magnetic pole that vibrates at a certain frequency; the pole is wrapped in copper wire which picks up an electrical current, and is then transmitted to an amplifier, which takes that signal and boosts it and then has it go into a speaker, where a copper wire is wrapped several times in a coil which when powered creates an alternating polarity magnet that attracts and repels a static magnet attached to the speaker cone in the speaker at the frequency that correlates to the frequency air vibrates to make us hear the pitch of the string played).
Wireless chargers are much the same: the charger and the phone both have a coil of wire in them, the alternating magnetic field of the charger then moves the coil of wire in the phone and transfers the charge. The heat you feel is from the battery absorbing that power and heat bleeding off/energy being wasted either from the wire having excess energy or the battery working very hard and creating heat.
For a stove, it’s just an electric current running through a piece of metal that resists it somewhat; it takes that energy and heats up due to the excess energy that it can’t handle being pumped through it leeching off. This one will heat your hand, so careful.
As for what electromagnetism *is*… that’s one that there’s barely an ELIPhD for, but the answer that is best lies in some tricky quantum mechanics stuff and is over my head, non-STEM grad that I am.
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