Kuormitusvaikutus

Kuormitusvaikutus refers to the phenomenon in electrical engineering and physics where the impedance of a measuring instrument or circuit affects the behavior of the circuit being measured. When a device is connected to measure a quantity, such as voltage or current, it draws some power or current from the circuit. This drawing of power alters the original conditions of the circuit, leading to a measurement that may not accurately reflect the circuit's state without the measuring device present.

The magnitude of the kuormitusvaikutus depends on the relative impedances of the source circuit and the measuring instrument. If the measuring instrument has a much higher impedance than the source circuit, its effect will be minimal. Conversely, if the instrument's impedance is comparable to or lower than the source circuit's impedance, the kuormitusvaikutus can be significant, leading to inaccurate readings.

For example, when measuring voltage with a voltmeter, the voltmeter has a finite internal resistance. This resistance is in parallel with the part of the circuit across which the voltage is being measured. If the voltmeter's resistance is not sufficiently high, it will draw current, causing a voltage drop across the internal resistance of the source, thus altering the voltage being measured. Similarly, an ammeter, which has a very low internal resistance, is placed in series with the circuit to measure current. If its resistance is not low enough, it will impede the flow of current, changing the actual current in the circuit. Minimizing kuormitusvaikutus is crucial for accurate measurements and is achieved by designing measuring instruments with appropriate impedance characteristics.