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# What is the use of negative voltage. if it do same as positive voltage? Answered

Some where we can see that the circuit only require negative voltage. WHY Only Negative IF positive voltage can do the same

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## 3 Replies

Voltages are always a difference in electrical potential energy between two points. Electrons will only flow from a more negative point to a more positive point if given the opportunity with a circuit.

Say you have 2 AA batteries in series, connected with a wire to a resistive load, then back around to the other side.

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Zero volts simply implies there is no electricity flowing between points connected to that area; It doesn't mean there is no electricity flowing THROUGH that area, just that internally that point will not flow.
The point between them (where they meet) you can consider zero volts. If you measure from that point to the negative lead on the left battery you'll find negative 1.5 volts. If you measure between that middle point and the positive tip of the right battery, you'll find POSITIVE 1.5 volts. If you measure between negative of one and the positive of the other, you'll find 3 volts, etc.

Why is it important? Knowing which way electricity flows (either actual electrons, or positive 'conventional' current, which was named before they knew about electrons flowing) is important for (mostly) one big reason: semiconductors usually only conduct in one direction. The technology that enabled the information age (the transistor) is generally a one-way switch (with some exceptions) Some circuits require electrons to flow in one direction , but still need 'more' circuit to have further electrons flow further in that direction. This is a common problem in translating communications protocols where the circuits share a ground (zero volts) connection, but only one signal is uses positive voltage (compared to ground) to represent the data while the other uses a negative (compared to ground).

Likewise, in analog circuits where sound is a valid signal, zero volts represents the middle zero value. The alternating current waveform causes the speaker diaphragm to move from this middle position either in, or out, based on positive, and negative voltage. If there was only positive voltage, the speaker would have to slam against an end-stop every time it vibrated because 'zero volts' would be the 'wall' the speaker hits.

framistan (author)2012-10-27

electricity does not just "spew" out of the terminal like a water faucet. Electricity travels in a CIRCLE out of the battery.... through the lightbulb or other item..... then back to the battery.

steveastrouk (author)2012-10-27

Circuits using "only "negative supplies are making sure that the highest side is actually at ground potential.