But why is it that only ferromagnets can actually be heated?

First of all, if you studied college physics, you won't miss the point like the people upstairs, and I think the focus of your question is why eddy currents have a stronger effect on ferromagnetics than other metals. Because in practice you have observed this, and in fact it is also true!

All I need are the two equations in Maxwell's equations. e=- b t and h=j+ d t, where h= 0 b is a known implicit condition, where is the relative permeability of the magnetic medium and 0 is the vacuum permeability! If you do not consider the displacement current d t, the second equation is the magnetic medium form of the Ampere loop theorem, you can write it yourself, compared with b=j0 0 (where j0 is the intrinsic current density, not the induced current density in the case of electromagnetic induction), h=j The greater the permeability of the magnetic medium, the greater its induced current i=(j-j0) s, and the largest permeability is the eighth period of ferromagnetism and its alloy!

In order to maximize the induced current, so that the thermal effect of eddy currents is more significant, ferromagnetic materials are used in induction cookers.

This is the only way to analyze from theory! I believe that the wise can see it!

Copper and aluminum are indeed conductors, but they can only conduct electricity, not magnetism, so copper and aluminum cannot be heated with an induction cooker.

Some metals are ferromagnetic, while others are not, and when the magnetic field acts on the ferromagnetic, it is magnetized, while other non-ferromagnetic materials are not.

Your conclusion is not right, you take a piece of aluminum and put it on the induction cooker, in the microwave oven, and in the intermediate frequency oven to see the results.

Do you mean that an induction cooker can't heat up a copper, aluminum object placed on it?

I don't think so. We know that the heating principle of induction cooker is that there are many coils inside, and by electrifying the coils, eddy currents are generated to generate heat, so as to generate usable heat.

Since the heat is generated inside the induction cooker. So it has nothing to do with putting copper or aluminum on the outside. Even if you put a piece of paper, it will still be heated.

It's not metal that can heat it. It must be a metal that can be magnetized (iron, cobalt, nickel) in order to be heated.

I'll give you a rough idea of why.

No matter what metal it is, why is it hot? In the end, it is the current that does the work. When you put a metal that can be magnetized into a changing magnetic field, an electric current will be generated in the metal, which will form eddy currents and generate heat.

When you put a metal that can't be magnetized into it, can you generate a vortex current to generate heat?

Also, I add, some people will say that taking a metal that cannot be magnetized and putting it on an induction cooker can also get hot. This is because an iron block inside the induction cooker undergoes a process that can be heated by the vortex current described above, and then the heat is transferred to other objects.

In fact, only ferromagnetic substances can be heated" is it written in the book?

The higher the temperature, the less magnetic it is, and when it reaches a certain temperature, the magnetism disappears.

When a magnet. When the temperature of the magnet increases, the more intense the molecular movement of the magnet, the more violent the disordered collision between the molecules, which breaks the balance of the molecular order, and the magnetism will weaken a lot. When the temperature rises to a certain value, there is a vigorous molecular thermal movement.

Finally, the regularity of the direction of electron motion is completely broken, and the magnetism of the magnet disappears. Metallurgists refer to the temperature at which magnets and magnets completely lose their magnetism"Curie temperature.

The Curie temperature of steel is 770.

The applications are as follows:

1. Electroacoustic device: mobile phone, TV, stereo, headphones and other sound-generating speakers, this kind of speaker is a device that converts electrical signals into acoustic signals. It is mainly composed of a fixed permanent magnet, a coil and a conical paper cone.

When the sound passes through the coil in the speaker in the form of audio current, the magnetic field generated by the magnet on the speaker will exert force on the coil, and the coil will vibrate at different frequencies due to the change of current intensity, and then drive the paper cone to emit different frequencies and strengths. The paper cone transmits the vibrations through the air, and the sound we hear is generated.

2. Electronic devices: dormant holstery holsters for mobile phones and tablets, etc.

3. Many items such as bags and holsters use magnets to adsorb and fix.

4. Medical field: the most commonly used MRI in medical examinations. It is to use the magnetic field of the human body itself and the magnetic material carried by the instrument itself to interact with each other to form a detection and development to help people see the cause of the lesion.

Similarly, in other medical treatments, there are also many traces of the application of magnets, such as acupuncture and moxibustion, magnetic therapy, magnetic detectors, etc.

5. Conversion devices for electric energy and kinetic energy such as motors and motors.

6. Magnets are also widely used in household appliances, such as induction cookers, microwave ovens and other electrical appliances.

If the temperature is too high, the magnetism disappears completely, and there is generally no magnetism after cooling.

But if the temperature is not too high, the magnetism is just weakened, ordinary magnets, after cooling, can recover some, some can recover all, the upstairs said rice cooker insulation magnetic switch is this reason, after the rice is cooked, the thermal conductivity decreases, the temperature continues to rise, the rice cooker switch can not absorb the power off, but it does not affect your next use.

Yes, it will even disappear! High temperatures destroy magnetic fields!

When a magnet is heated to a certain temperature, it will suddenly lose its magnetism, which is caused by the arrangement of the many "meta-magnets" that make up the magnet from ordered to disordered; When a magnet that loses its magnetism is placed into a magnetic field, when the magnetization reaches a certain value, it is magnetized again, and the arrangement of the "meta-magnets" changes from disordered to ordered.

As the temperature of magnets and magnets increases, the thermal movement of molecules inside them becomes faster and faster. As a result, more and more electrons refused to listen"Queue up"of"Password"Finish. When the temperature rises to a certain value, the violent molecular thermal motion finally completely destroys the regularity of the direction of the electron motion, and the magnetism of the magnet disappears.

Metallurgists refer to the temperature at which magnets and magnets completely lose their magnetism"Curie temperature. "。The Curie temperature of steel is 770°C.

Now, you should know why a red-hot magnet can't attract iron nails. Because of the red-hot magnet, the general temperature has exceeded 800°C. Of course, if we re-magnetize the magnet after the temperature drops, it will still be able to re-magnetize"work"Get up.

When a magnet is heated, is it still magnetic? I don't believe myself anymore.

Yes, it will even disappear! High temperatures destroy magnetic fields!

When a magnet is heated, does its magnetic properties change? Let's see how foreigners operate.

Magnets are magnetic because of iron, cobalt, nickel, or ferrite.

Other ferromagnetic substances differ from the spin of electrons inside it.

It can be arranged spontaneously in a small area, forming a spontaneous magnetization zone, which is calledMagnetic domains

After the ferromagnetic material is magnetized, the internal magnetic domains are arranged neatly and in the same direction, so that the magnetism is strengthened, and the magnet is formed. The process of magnet iron attraction is to the iron block.

The magnetization process produces an attractive force between the magnetized iron block and the magnet with different polarities.

The iron is firmly "glued" to the magnet. Let's say that magnets are magnetic. However, high temperatures change this particular internal structure, resulting in the loss of magnetism.

The principle of the magnetic field of celestial bodies is different, and in layman's terms, it is because the surface of the celestial body is charged with gas (the sun) or the interior is charged with magma.

Earth) (of course, the above is only the most accepted hypothesis, and is inconclusive, and is only used here to distinguish it from magnets).

Personally, I think that magnets do lose their magnetic physical phenomena in the ultra-high temperature stateIn fact, it only loses the part of magnetic opposite-sex attraction in the ultra-high temperature state, and the same-sex repulsion and magnetic field coil in the magnetism still exist.

Because, in the universe, all visible physical matter is made up of atoms, and the atoms are subdivided into nuclei.

It is composed of many electrons on the periphery.

The phenomenon of infinite natural circulation of electrons around the nucleus of the atom will naturally produce the magnetic physical phenomenon of the atoms of the solid substanceIn other words, all celestial bodies in the universe naturally have their own magnetic phenomena.

The electromagnet burns red, and the molecules inside it heat up all over the place, disrupting the consistency of the direction of electron motion.

Magnetism is ordered, and high temperature is the intensification of particle motion, and the order of magnetism is broken by a certain program, and magnetism is gradually lost with the increase of temperature.

Because the high temperature will interfere with the magnetism inside the magnet.

Whether it is ferrite, rare earth, alnico permanent magnet materials will lose their magnetism due to accelerated thermal movement at high temperatures.

The magnetic effects cancel each other out, so the whole "magnet" no longer shows magnetism.

The high temperature can cause problems on the inside of the magnet.

Because high temperatures are devastating for magnetic damage.

The molecules in the magnet are destroyed.

At high temperatures, there is a molecular disorder in the magnet.

Because the high temperature will inactivate the magnet.

It can throw the neatly arranged molecules out of balance.

The decrease in energy caused by the parallel arrangement of spins in a broken magnet at high temperatures.

Magnetic ** are the molecules inside the magnet, and high temperatures affect them.

Because the magnet will be destroyed at high temperatures, it is a kind of magnetism in the body of this post.

It will cause the molecular disorder inside the magnet to lose its magnetism.

Because the nature of the i magnet is unstable, it will not be there when it encounters high temperatures.

This is because magnets are unstable in nature at high temperatures.

Because it will be the electrons that are disordered.

At high temperatures, the electrons become disordered.

Magnetic ** are the molecules inside the magnet.

The nature of magnets is unstable.