Some do some don't.
The polarity reverse at each firing
Reversing polarity ,changes the rotation of the device you are changing polarity on.
Reverse the polarity of the magnet.
If, by 'reverse polarity', you mean the accidental reversal of the line and neutral conductors at the socket outlet or receptacle, then the answer is no.
i don't believe you can reverse the polarity on a fuse, they simply regulate the amperage of the circuit they protect,
multiply by -1...
yes
Reverse polarity with a portable jump starter occurs when the positive and negative clamps are connected to the wrong terminals on the battery. This can cause damage to the jump starter, the vehicle's electrical system, and the battery itself. It is important to always double-check the polarity before connecting the jump starter to avoid this issue.
i would never naturally assume any circuitry to be "reverse polarity" by default even if they are. since this can fry a lot of IC, and micro controllers. there are several options to adding a reverse polarity protection circuit to your project you can find three easy to implement circuits here: http://provideyourown.com/2012/reverse-polarity-protection-circuits/
Normal polarity.
we will have straight polarity and reverse polarity,we can produce the weld with good quality
The case of reverse polarity would only happen on a DC system. As to would it cause equipment to run when switched off, no, if the switch opens the equipment's power supply completely the device will not operate.