What principle allows a moving coil meter to work?

A moving coil meter operates based on the principle of electromagnetic torque generated by a coil placed within a magnetic field. When an electric current flows through the coil, it creates a magnetic field around the coil that interacts with the external magnetic field, typically provided by permanent magnets. This interaction results in a torque that causes the coil to rotate, which moves the pointer on the meter's scale. The amount of current flowing through the coil determines the degree of rotation, allowing the meter to indicate the current level or voltage if used in a different configuration.

This principle is fundamental to the design and functionality of moving coil meters, making them effective for measuring current and voltage in various applications. The other concepts listed, such as magnetic induction or resistance measurement, do not directly apply to how the moving coil meter operates. The mechanism relies specifically on electromagnetic forces, distinguishing it from those other electrical principles.