What is the only measurement capability of the basic meter movement?

The basic meter movement, particularly in the context of analog measuring devices, is fundamentally designed to measure current. This capability arises from the principle of how such meters operate; they use a moving-coil system where the current flowing through the coil produces a magnetic field that interacts with a stationary magnet, causing the coil (and the attached needle) to move.

This movement is directly proportional to the amount of current passing through the meter, making current measurement its primary function. In technical terms, it is often referred to as an ammeter when solely intended for this purpose.

While voltage is also often measured with a meter, this requires additional circuitry (like a voltage divider) and is not a function of the basic meter movement itself. Power measurement often requires simultaneous current and voltage readings, which the basic meter movement cannot provide by itself. On the other hand, resistance measurement involves applying a known voltage across a resistor and measuring the resulting current, typically requiring a separate setup or device from the basic meter movement. Thus, the correct focus on current highlights the fundamental capability inherent in the design of the basic meter movement.