Attenuators are usually passive devices made from simple voltage divider networks. A variable resistor would dissipate power as heat and acts as a voltage divider. The two resistors R and R act only as a "pure" attenuator (voltage divider). In this case, the voltage divider R1-R2 compensates the voltage variations to some extent. "The voltage divider is formed using external resistors" R and R. However, if formula 5, it and formula 6 together form a voltage divider. The two resistors R and R form another voltage divider that determines the high threshold. Comparatively, voltage divider is used to satisfy Kirchhoff's Voltage Law (KVL). In electric power transmission, a capacitive voltage divider is used for measurement of high voltage.