If the resistance is what make heating elements heat up , then is it ideal for me to use something close to an insulator as a heating element?
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\$\begingroup\$ What are you trying to achieve? You can make a heating element out of Nichrome wire see en.m.wikipedia.org/wiki/Nichrome \$\endgroup\$– mhaselupCommented Aug 6, 2020 at 8:35
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\$\begingroup\$ That's an instesting idea, but it's not how its normally done usually the heatign element is something that is conductive, A TIG welder forms a heating element from argon gas but even then it converts it into a conductive form. \$\endgroup\$– Jasen Слава УкраїніCommented Aug 6, 2020 at 13:06
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4 Answers
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The goal of the heating element is to pass current through. The power dissipated as heat is V*I = I^2 * R. So you need something that DOES conduct. Besides, dependence on current, as you see, is quadratic. So if we reduce resistance by N times, we increase current by N times, you have N^2/N = N times increase in heat output. Since insulators don't conduct (infinite resistance, zero current), how are they supposed to be heating elements and get hot? I googled the nichrome as suggested by @mhaselup, and its resistance is extremely small. Other than that, it has some other important properties like withstanding high temps and oxidation. Have a look: heating element materials
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No, by definition an insulator does not conduct electricity therefore it cannot heat up as the result. The power dissipated by a load is I^2*R. If I=0 then P=0.
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\$\begingroup\$ Thanks mhaselup . But I meant close to an insulator ,like something with a high resistance \$\endgroup\$ Commented Aug 6, 2020 at 11:05
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\$\begingroup\$ Ok. Looking at it another way the power dissipated by a resistance is V^2/R so for a fixed voltage V the heat produced is inversely proportional to the resistance R. As R increases it becomes a less efficient at generating heat. So a high resistance would make a poor heater. \$\endgroup\$– mhaselupCommented Aug 6, 2020 at 11:23
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\$\begingroup\$ @muhammedAbdulquadri You're mixing up some subtleties. It's still the current that does the heating as outlined by mhaselup due to I^2R. The amount of current plays a much bigger role than the resistance. The reason "resistance wire" with high resistance rather than regular low resistance wire is used as a heater isn't because high resistance heats up more. It's because it lets you not need to use unreasonably low voltages and unreasonably high currents. It does not mean that really high resistance makes a better heater. \$\endgroup\$– DKNguyenCommented Aug 6, 2020 at 13:17
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The heating element really needs to be matched to whatever power supply you intend to use to drive it.
The power is given by P = V x I, where V is the voltage and I is the current.
Applying Ohm's law, V = I x R, we can also work out two more equations for the power:
P = I² x R and P = V² / R.
A consequence of that last equation is that if you want to use a very high resistance as a heater, then you will need a high voltage to drive it. It's often easier to use a (safer) lower voltage, and adjust the resistance accordingly.
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To answer the title question, sure you can. For example, ferrite is a poor conductor, but can be heated using RF (microwaves).
If you want to use the material as part of a resistance heater (using DC or low frequency AC), and you have a power supply voltage V, the power is described by \$V^2/R\$, so you match the resistance to the supply voltage to get the desired power. Too low and you draw too much current and the power may be high enough to damage the material, too high and you don't get much power.
The typical problem in designing a heater is that high temperature conductive materials are a bit too conductive for convenient voltages so you have to make the material very long and thin to get enough resistance. Recall that resistance is \$\rho\cdot L/A\$ where \$\rho\$ is the material resistivity, L is the length of the element and A is the cross-sectional area.
It would, indeed, be nice if there was a material that could withstand 1600° in air, was relatively inexpensive and would have resistivity 10x or 100x that of Nichrome. In fact, sometimes we have to use inconveniently low voltages in order to design heaters (such as Mo rods) that will stand up.
answered Aug 6, 2020 at 13:11