How a heating element is connected to increase power

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  • #26
.Scott
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If the resistance of the heater is halved then the current is doubled (assuming same voltage power supply).
This means that the power is doubled....doesn't this suggest that lower resistivity is an advantage?
It could be. But let's say you divided it by 100. The current would increase by a factor of 100 and the entire circuit would burn itself out.
In general, you are looking for a specific heat output for your heating element. So if you used a material of lesser resistance, you could use a thinner or longer piece to get the same resistance and therefor the same power (heat) output. But if you pick something with very low resistance, this can get to be a problem. If it is too long and this, it may be too fragile.
 
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  • #27
.Scott
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I may be wrong here but does 'specific heat' count? Would 'lower specific heat' be a desirable property for a heating element?
Specific heat could be important. It would affect how much energy is required to heat up the filament itself. Combined with the thermal conductivity, it would help keep the entire filament at one temperature. This is important because a small defect in one part of the filament could make that spot more resistive and therefore generate more heat. So a small defect can overheat causing a larger defect causing more heat, etc. Keeping the filament at the same temperature keeps these defects from growing as quickly.
 
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It could be. But let's say you divided it by 100. The current would increase by a factor of 100 and the entire circuit would burn itself out.
In general, you are looking for a specific heat output for your heating element. So if you used a material of lesser resistance, you could use a thinner or longer piece to get the same resistance and therefor the same power (heat) output. But if you pick something with very low resistance, this can get to be a problem. If it is too long and this, it may be too fragile.
What do you mean by "specific heat output"..... The original post refers to "power"
You cannot be sure that increasing the current by a factor of 100 would 'burn out the entire circuit' without more details.

The principals are what matters
 
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  • #29
.Scott
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What do you mean by "specific heat output"..... The original post refers to "power"
You cannot be sure that increasing the current by a factor of 100 would 'burn out the entire circuit' without more details.

The principals are what matters
True enough. In the original circuit, we started out generating 750W. Reducing the resistance by 100 has the potential of generating 75KW. Assuming your original 240-volt power source was capable of generating 75KW, your 3.49 meter long, 1.0mm wide ribbon would now be dissipating heat at about 215 watts per centimeter. So, "burn out the entire circuit" was inaccurate. Perhaps you trip a breaker. Perhaps you detonate your filament. Perhaps you burn out your 240V generator. Perhaps you do all three. I only meant to communicate the notion of "something bad happens".
 
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