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Reverse polarity means connecting a power source, or polarised componenet, with the positive and negative poles the wrong way round.

If the positive and negative supply is connected the wrong way round in electronic devices, it usually causes damage, because semiconductors are sensitive to polarity.

Sometimes protection is provided, so that reverse polarity stops the device from working without causing damage.

Connecting a diode (or rectifier) in reverse, will block the flow of current, without causing damage and is useful in protecting circuits from reverse polarity.

In some consumer electronics (especially CB Radios) the power input has a recitifier across the 12v supply.

If it is wired correctly, the rectifier is in reverse polarity, does not conduct and allows the radio to work.

If you reverse the polarity of the power supply, the rectifier is now in full conduction, across the supply, causing a dead short. This shunts any power away from the radio and blows the fuse in the line, thus protecting it.

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14y ago

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