What’s the difference between negative and ground in circuits?
In: Engineering
In electronics, “ground” is a somewhat ambiguous term, since it has multiple meanings that depend upon the situation. It can be a little confusing.
One of the uses of “ground” is in safety ground or earth ground. That’s what the third prong (in the USA) of some plugs are. They literally are connected eventually to the ground. Usually the chassis or case of a device is hooked up to earth ground, so that if there’s a short circuit it will channel current to the earth rather than a user. This also helps avoid unwanted emission of radiation.
More often, “ground” simply refers to a common point in a circuit that is considered the 0 volt reference point. It isn’t necessarily truly at 0 volts but that doesn’t matter since voltages are always relative to each other. If a system is self-contained, it doesn’t matter if the ground is not really 0 volts (the same potential as the Earth).
In many circuits, all of the voltages are positive. So the ground is connected to the negative terminal of the battery or power supply, and the circuit’s “power” comes from the positive terminal.
There are circuits that use both positive and negative voltages (such as many operational amplifiers). In those cases, there are 3 (or more) power supply voltages available…positive, negative, and ground.
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