Question

I would be very happy if I get any help with any of this questions. And I am sorry if I make any grammatical mistakes, I don't know grammar well. I guess, the problem for understanding how resistance works is my poor understanding of quantum mechanics.

I heard about thermistors. NTC thermistors are made from semiconductors in a ceramic body. Another question, why there is such ceramic body? Is it mainly for structure durability and heat conducting reasons?(I am not sure about properties of ceramics in electronics) According to wiki, PTC thermistors are usually prepared from barium (Ba), strontium, or lead titanates (e.g. PbTiO3). So what is the reason for these specific materials?

I can somewhat understand about NTC ones, they use semiconductors. Perhaps, heating results in somewhat less probability of electrons staying in that occupied state due to boltzman distrubution, thus less probability of energy transfer to the conducting atom or molecules via relaxation. Also, less probability of electron being on the occupied state gives more probability of electrons to be on the conducting state. But, how more electrons in the conducting state available, makes resistance(heat dissipation due to electron current) lower? I am not sure. How resistance work?

PTC thermistors case: Conducting metal atoms start to jiggle around, thus creating more frictions to passing electrons. How can I understand it in a more quantum physics/chemistry/mechanics way? (just in case: I am 2nd year chemistry student who was trying to learn how to do basic electronic stuff on arduino or not and was learning resistors in more details by this video. Then, got curios about thermistor composition)

Also, why it is not the case in a other metal or carbon film resistors?

How metal's or any other material's expansion or compression upon heating effects the resistance? Maybe is it due to compression expansion? But barium expands upon heating meanwhile, in strain gauge expansion causes reduced resistance.

Answer 1

The resistance of a material is determined by the behavior of its electrons. In a conductor, electrons collide with particles, transfer kinetic energy, and cause resistance. NTC thermistors decrease resistance with increasing temperature, while PTC thermistors increase resistance. Expansion or compression of materials can also affect resistance.

Step-by-step explanation:

The resistance of a material is determined by the behavior of its electrons. In a conductor, such as a metal, electrons move through the material and collide with the particles of the conductor, transferring kinetic energy and causing the electrons to slow down. This transfer of kinetic energy leads to resistance and the heating up of the material. In the case of NTC and PTC thermistors, the resistance is affected by the temperature. NTC thermistors are made from semiconductors in a ceramic body, which provides structure durability and heat conduction. The resistance of NTC thermistors decreases with increasing temperature due to the increased probability of electrons being in the conducting state.

On the other hand, PTC thermistors are usually prepared from barium, strontium, or lead titanates. These specific materials have unique properties that result in the desired temperature-dependent resistance behavior. The conducting metal atoms in PTC thermistors start to jiggle around and create more friction to passing electrons, leading to an increase in resistance with increasing temperature. It is important to note that the expansion or compression of materials upon heating can also affect resistance. The expansion or compression of a material can alter its electrical properties and change its resistance. For example, the expansion of barium in a PTC thermistor causes a reduction in resistance.