Ideal Constant-Voltage Source
Ideal Constant-Voltage Source
It is that voltage source (or generator) whose output voltage remains absolutely constant whatever the change in load current. Such a voltage source must possess zero internal resistance so that internal voltage drop in the source is zero. In that case, output voltage provided by the source would remain constant irrespective of the amount of current drawn from it. In practice, none such ideal constant-voltage source can be obtained. However, smaller the internal resistance r of a voltage source, closer it comes to the ideal sources described above.
Suppose, a 6-V battery has an internal resistance of 0.005 Ω. When it supplies no current i.e. it is on no-load, Vo = 6 V i.e. output voltage provided by it at its output terminals A and B is 6 V. If load current increases to 100 A, internal drop = 100 × 0.005 = 0.5 V.
Hence, Vo = 6 − 0.5
= 5.5 V.
Obviously an output voltage of 5.5 − 6 V can be considered constant as compared to wide variations in load current from 0 A to 100 A.
Read article – Units of Resistivity
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