# what is analog and digital signal in electrical terms? [closed]

Analog signals are continous while the digital signals. In electrical terms digital signals are like +5 volts then 0 volts again +5volts , +5volts , 0volts and so on am i right???? and the analog signals are like +5volts 4.9volts, 4.8 volts, 4.7 volts and decrease up to 0 volts and then goes negative (by the way what is negative volt) and then rises up am i right?

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## closed as off topic by Warner, Chris S, Zypher♦, EEAA, sysadmin1138♦Jul 22 '10 at 21:05

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Smells like homework. –  Chris S Jul 22 '10 at 20:57

No, you're not right - not about your assumptions or about this being the place to ask this question - try wikipedia.

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Wikipedia: en.wikipedia.org/wiki/Analog_signal and en.wikipedia.org/wiki/Digital_signal with examples –  coredump Jul 22 '10 at 20:45

Analogue refers to a continuously varying quantity, so in your voltage example is partially correct - but there are an infinite number of values that it can take - usually over a range.

Digital refers to a value that can have only certain discrete values. This can be just two - 0V or +5V, but it could theoretically be more - three (-5V, 0V and +5V) for example.

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No are right, in some cases.

Defining a signal as digital or analog does not define the actual voltages used. This varies from system to system, depending on the components used.

It doesn't even need to be 0 and a positive voltage. A digital system could be -12 volts for off and +12 volts for on, or +24 volts for on and +6 volts for off!

The only thing you can be sure of is a digital signal will have discrete voltages to signify the different states and that Analog signals generally will vary over a range (nothing specifies the max or min cannot be theoretically infinity though).

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