Resistive loads in general

The circuits you have seen here are good for illustrating principles of direct current. But some of the circuits shown here have no relevance to the practicality. You'll never find a resistor connected across a battery, along with a couple of meters, as shown in the Figure, for instance. The resistor will get warm, maybe even hot, and it will gradually drain the battery in an unspectacular way. Apart from its educational value, the circuit does nothing of any use.

In real life, the ammeter and voltmeter readings in an arrangement such as that shown in Figure would decline with time. Ultimately, you would be left with a dead, cold battery, a couple of zeroed-out meters, a potentiometer, and some wire.

The resistances in the diagrams like Figure given are always put to some use in electrical and electronic circuits. Voltage division is a significant way in which resistors are employed.