Let's look at an ideal DC voltage source. It would supply a set voltage V0. Now attach an ideal wire to the + and - terminals of your ideal voltage source, and- Oh dear! The current has gone to infinity. Since we cannot have an infinite number of electrons moving through a wire, there has to be something else going on. In real life, the voltage source is made from real materials that have finite non-zero resistance, or, in other words, the voltage source has an internal resistance that limits the current that can be supplied at that voltage. If the demanded current is too high (low too low in resistance), the voltage of the output will drop to compensate, but it may also cause damage to the voltage source, as it will heat up at the rate P=I^2 R(internal). If the current doubles, the voltage supply heats up four times as fast.

The load has a significant effect on the output voltage of a practical voltage source. Unlike an ideal voltage source, which maintains a constant output voltage regardless of the load, a practical voltage source is affected by the internal resistance or impedance of the source itself. When a load is connected to a voltage source, if the load resistance is high, the current drawn from the source will be relatively small, and the output voltage will remain close to its nominal value. However, as the load resistance decreases (meaning the load draws more current), the output voltage of a practical voltage source will decrease due to the internal resistance of the source. This is because the internal resistance causes a voltage drop within the source, reducing the voltage that appears across the load. The effect of the load on the output voltage becomes more noticeable when the load requires significant current. For example, if a heavy load, such as a motor, is connected to the voltage source, the voltage drop across the internal resistance of the source can cause a noticeable reduction in the output voltage supplied to the load. In summary, as the load increases its current demand, the output voltage of a practical voltage source decreases, especially if the internal resistance of the source is significant. This is one of the reasons why voltage regulation is an important feature of practical voltage sources. Visit https://electricityforum.com to get more info.