What does a galvanometer measure?

A galvanometer is specifically designed to measure small electric currents. It operates on the principle that an electric current running through a coil situated in a magnetic field will produce a torque on the coil, resulting in a deflection of the pointer on a scale. This deflection is proportional to the current flowing through the coil, allowing for the measurement of very low levels of current with high sensitivity.

The nature of a galvanometer is such that it cannot effectively measure high electric currents, as it may be damaged or produce inaccurate readings under such conditions. It is also not designed to measure voltage levels or electric resistance, as those require different types of instruments such as voltmeters for voltage and ohmmeters for resistance. Thus, its primary function is to detect and measure small currents, making it a vital tool in various electrical and electronic applications.