Analogue ammeter. This device is used to measure electrical current (the amount of electrons flowing past a point in the circuit). This is measured in amperes (amps), and is closely related to the voltage of the power source and the resistance of the circuit. This is an analogue ammeter, using a moving needle to indicate a point on a dial, as opposed to digits on a screen (digital). The ammeter is connected to the circuit at the black and red points, with the option of connecting to either the 5 amps or 1 amps points (with two corresponding scales on the dial). This model, from Ravencourt, has a negative region on the dial, allowing it to be calibrated to a zero point.