An instrument can measure the electric current called an ammeter. To measure current ammeter must connect in series with the circuit whose current is to be measured.

The measurement of current through the resistor by using an ammeter is shown in the below figure.

The electric current can also be measured using a galvanometer. The galvanometer gives both the direction and the magnitude of the electric current.

The current can be measured by detecting the magnetic field associated with the current without breaking the circuit. There are various instruments used to measure the current without breaking the circuit.

• Hall effect current sensor transducers
• Current transformer (CT) (Only measure AC)
• Clamp-on meter
• Shunt resistors
• Magneto resistive field sensors