It is a 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 source described above.
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 source described above.
Suppose a 6V
battery has an internal resistance of 0.005Ω as shown in figure 1 below;
battery has an internal resistance of 0.005Ω as shown in figure 1 below;
When it supplies
no current that is, it is no load, VO = 6V. That is output voltage
provided by it at its output terminals A and B is 6V. If the load current
increases to 100A, internal drop = 100 x 0.005 = 0.5.
no current that is, it is no load, VO = 6V. That is output voltage
provided by it at its output terminals A and B is 6V. If the load current
increases to 100A, internal drop = 100 x 0.005 = 0.5.
Hence, VO
= 6 – 0.5 = 5.5V.
= 6 – 0.5 = 5.5V.
Obviously, an
output voltage of 5.5 from 6V source can be considered constant as compared to
the wide variation in load current from 0A to 100A.
output voltage of 5.5 from 6V source can be considered constant as compared to
the wide variation in load current from 0A to 100A.
