What is the input impedance of a digital multimeter set to read voltage?

The input impedance of a digital multimeter set to read voltage is high compared to the circuit impedance. This characteristic is crucial because a high input impedance helps to ensure that the multimeter does not significantly affect the circuit being tested.

When measuring voltage, the multimeter connects in parallel with the circuit components. If the input impedance were low, it would draw substantial current from the circuit, altering the voltage being measured and potentially leading to incorrect readings. By having a high input impedance, often in the range of 1 MΩ or higher, the multimeter minimizes its impact on the circuit, providing a more accurate representation of the voltage across the component or points being measured.

In contrast, a low input impedance would mean that the multimeter could affect the circuit too much, while a variable impedance might lead to inconsistent readings depending on the circuit conditions. An input impedance of zero would effectively short-circuit the points being measured, resulting in a complete failure to provide any meaningful measurement. Thus, having a high input impedance is the desired attribute for a multimeter when measuring voltage.