Jännitemittareissa

Jännitemittareissa, commonly known as voltmeters, are essential electrical test instruments used to measure the electrical potential difference between two points in an electric circuit. This potential difference is also referred to as voltage. Voltmeters are crucial for diagnosing electrical issues, verifying circuit operation, and ensuring safety.

The primary principle behind most voltmeters is their high internal resistance. This is a critical design feature because it minimizes the current drawn from the circuit being tested. If a voltmeter had low resistance, it would draw significant current, thereby altering the very voltage it is intended to measure, leading to inaccurate readings. Modern voltmeters can be analog or digital. Analog voltmeters utilize a moving coil galvanometer to display the voltage, with a needle deflecting across a calibrated scale. Digital voltmeters, on the other hand, convert the analog voltage signal into a digital format and display it numerically on an LED or LCD screen. Digital voltmeters generally offer higher accuracy and easier readability.

Voltmeters are connected in parallel across the component or section of the circuit where the voltage is to be measured. This parallel connection ensures that the voltmeter receives a voltage drop proportional to the voltage across that part of the circuit. They are typically equipped with probes or leads that are touched to the desired points. It is important to select a voltmeter with an appropriate range for the expected voltage to avoid damage to the instrument. Understanding the polarity of the voltage is also important when making measurements, especially with direct current (DC) circuits, to ensure correct readings.