Explain the effect of an internal resistance on the voltage and current that can be provided by a voltage source, compared to if the source was ideal.

An ideal voltage source can provide a constant voltage across its terminals regardless of the current flowing through it. However, in reality, all voltage sources have some amount of internal resistance. This internal resistance can affect the voltage and current that the source can provide in the following ways:

1. Effect on Voltage: When current flows through the internal resistance, there will be a voltage drop across this resistance (according to Ohm's law: V = IR). This means that the voltage available at the terminals of the source will be less than the actual voltage of the source. The more the current drawn from the source, the more the voltage drop, and hence, the less the terminal voltage.

2. Effect on Current: The internal resistance also limits the maximum current that can be drawn from the source. According to Ohm's law, the current I = V/R. So, if the internal resistance is high, the current provided by the source will be less.

In summary, the presence of an internal resistance in a voltage source reduces the terminal voltage and limits the current that can be drawn from the source, compared to an ideal voltage source.