Which one of the following gives the V - I characteristic of an ideal voltage source?

Explanation:

• In every practical voltage source, there is some electrical resistance inside it. This resistance is called the internal resistance of the source.
• When the terminal of the source is open-circuited, there is no current flowing through it; hence there is no voltage drop inside the source but when the load is connected with the source, current starts flowing through the load as well as the source itself.
• But in an ideal voltage source, this difference is considered as zero that means there would not be any voltage drop in it when current flows through it and this implies that the internal resistance of an ideal source must be zero.

This can be concluded that voltage across the source remains constant for all values of load current.

The V-I characteristics of an ideal voltage source are shown below.

Ideal case with noise effect,

Considering the effect of noise, Ideal Voltage Source delivers constant voltage irrespective of the value of current through it and V-I characteristics are given as:

Hence, option (3) is the answer.