Ideal Voltage Source vs Practical Voltage Source
An ideal voltage source is the simplest model for a voltage source. We can use a more accurate model
The voltage of a practical voltage source decreases as the voltage source supplies more power
Under certain conditions the nonideal voltage source and nonideal voltage source are equivalent
When you replace a nonideal voltage source with a nonideal current source or vice versa and it does not change any currents or voltages in the rest of the circit it is attached to, you have preformed a source transformation