The piece of equipment used to measure the current in a circuit is called an ammeter. An ammeter is connected in series with the circuit component through which the current is being measured, ensuring the current flowing through the ammeter is the same as that flowing through the component. It has very low internal resistance to avoid significantly affecting the circuit operation during measurement. Another common tool that can measure current indirectly is a current clamp, which measures the magnetic field around a conductor to infer the current flow. Multimeters often have ammeter functions to measure current directly by breaking the circuit and inserting the meter in series.