Resistive loads in general

The circuits you’ve seen here are good for illustrating the principles of dc. But some of the circuits shown here have essentially no practicality. You’ll never find a resistor connected across a battery, along with a couple of meters, as shown in Fig. 1, for example. The resistor will get warm, maybe even hot, and it will eventually drain the battery in an unspectacular way. Aside 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 Fig. 1 would decline with time. Ultimately, you’d be left with a dead, cold battery, a couple of zeroed-out meters, a potentiometer, and some wire. The resistances in the diagrams like Fig. 1 are always put to some use in electrical and electronic circuits. Instead of resistors, you might have light bulbs, appliances (60-Hz utility ac behaves much like dc in many cases), motors, computers, and radios.
Voltage division is one important way in which resistors are employed. This, along with more details about current, voltage, and resistance in dc circuits.

Fig. 1: Circuit for working Ohm’s Law problems.