What does a voltage tester need to achieve in order to operate effectively?

For a voltage tester to operate effectively, it must have high resistance. This design characteristic is crucial because it minimizes the impact of the tester on the circuit being measured. High resistance ensures that the tester draws very little current from the circuit, allowing it to accurately measure the voltage present without significantly altering the electrical conditions of that circuit. This is especially important in sensitive electronic applications where even a small change in current can lead to inaccurate readings or damage to the component being tested.

In contrast, if a voltage tester had low resistance, it could cause a significant load on the circuit, potentially leading to erroneous readings or even creating a fault condition. Thus, the requirement for high resistance in voltage testers is essential for reliable and precise voltage measurement.