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# What voltage can heat gauge 24 nichrome wire 30 cm long successfully? Am building a polythene sealing machine

Am building a polythene sealing machine using nichrome wire, I use 9v battery but is not heating. What voltage should I used and can I use ac or dc

## Comments

2 years ago

I have a plastic bag sealer, with a single wire heating element with approximately the same dimensions you describe.

Upon request, I can measure the power (the product of voltage times current) dissipated by that wire when it is energized.

The actual like, figure of merit you want, is probably something like the power dissipated by the wire, divided by its length, or surface area, or something like that.

AC or DC does not matter. In fact the formulas for Ohm's law, and dissipated power are the same for AC as for DC, except that when you do the math for AC, you use RMS voltages and currents.

By the way, a 9V battery is kind of a joke for any application requiring more than about 1 watt of power, and you can prove this to yourself, by actually measuring the voltage across your length of nichrome wire, like, with your voltmeter. Or equivalently, measure the voltage across the battery's terminals, and then watch what happens to the battery voltage when you connect a length of nichrome wire across it.

My guess is the voltage under this load will be closer to zero, than it will be to 9 volts.