Because it is important to use the right kind of voltmeter, they are most often made so they can be adjusted to measure all kinds of voltages. Such voltmeters usually have a "knob" or switch that can be set in different ways. If the voltmeter is set in one way, the voltmeter handles voltages up to, for example, 10 volts. If the switch is set in another way, the voltmeter can handle 100 volts, and so on. Inside the voltmeter, the switch usually works by changing resistors in a voltage divider.