A meter has a full-scale deflection of 40 microamperes and an internal resistance of 96 ohms. You want it to read 0 to 1 mA. The value of the shunt to be used is:

To increase the range of a current meter, a shunt resistor is placed in parallel to bypass the excess current. The total desired current is 1 mA (which is 1000 µA). Since the meter can only handle 40 µA for full-scale deflection, the shunt must carry the remaining current: 1000 µA - 40 µA = 960 µA. Because the meter and the shunt are connected in parallel, the voltage drop across them must be identical. First, find the voltage drop across the meter using Ohm's Law (V = I * R): 40 µA * 96 ohms = 3840 µV. Next, use that same voltage to find the required resistance of the shunt (R = V / I). Divide the voltage by the current flowing through the shunt: 3840 µV / 960 µA = 4 ohms. The other answers represent incorrect arithmetic or confusing parallel formulas with series multipliers.