Why is low voltage used to control high voltage?

Low voltage used to control high voltage because the circuits that operate at high currents or high voltage cannot be directly controlled by an Arduino. The only way to control high voltage is the low voltage, this give the signal or relay from Arduino and which is capable to handle and switch high voltage.

answer: try staring at an object, like a poster or something as a start : )

the cdc / centers for disease control and prevention

explanation: