Is it possible to heat nichrome wire with 0.5V 20A?
what is the different between heat produced by 0.5v 20A (10watt) and 10v 1a (10watt) ?
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\$\begingroup\$ Depends on how thick and long the wire is. \$\endgroup\$– Ignacio Vazquez-AbramsCommented Sep 8, 2015 at 20:06
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\$\begingroup\$ i am already have two wire..i want to know the different between heat produced by 0.5v 20A (10watt) and 10v 1a (10watt) ? \$\endgroup\$– hertz12Commented Sep 8, 2015 at 22:35
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\$\begingroup\$ Once you have the wire (R) and it's length selected you are stuck. For a given power (P), there is only one I,V combination that will satisfy V = IR and P = IV simultaneously. \$\endgroup\$– Houston FortneyCommented Sep 9, 2015 at 1:48
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1 Answer
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Nichrome has a certain resistivity (which varies with temperature and exact alloy). To use a lower voltage means you have to have lower resistance, all other things being equal. Resistance of the wire is:
\$\rho L/A\$ where \$\rho\$ is the resistivity of Nichrome, L is the length of the wire and A is the cross-sectional area of the wire (\$\pi r^2\$ if the wire is round).
In your two examples, the resistance is 25m\$\Omega\$ or 10\$\Omega\$, a 1:400 ratio.
If the wire is fixed length (for example for a wire foam cutter) then the lower voltage wire must be \$\sqrt{400}\$ times larger diameter or 20:1.
The heat loss will be a bit different with the different sizes of wire. There is a good set of tables on Wikipedia.
answered Sep 8, 2015 at 20:19
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\$\begingroup\$ Additionally, the lower resistance wire will have a lower efficiency considering any resistance in other components (source internal impedance, wiring to source, etc.). \$\endgroup\$ Commented Sep 8, 2015 at 21:07