Electrical multimeters, or multitesters, are widely used by technicians when working with electrical and electronic circuits. In this instrument, a single milliammeter connected through different resistances is used to measure currents, potential differences and resistance over different ranges. Current always enters the multimeter at the same terminal, A, and then passes through the milliammeter as well as through other resistances, placed in series with or parallel to it. The choice of the terminal at which current leaves the instrument decides its role (ammeter, voltemeter, etc.) and its range (maximum current or voltage whichit can measure). The milliammeter shown in the circuit has a coil (or internal ) resistance of 0.9 omega and gives the full-scale deflection for a current of 10mA. If A and B are used as the terminals of the multimeter, i.e., current enters at A and leaves at B, it will function as an ammeter of range