Question 70

The Correct Answer is B ### Why Option B is Correct An **ammeter** is designed to measure the current flowing *through* a specific point in a circuit. To do this, the ammeter assembly (which includes the shunt and the meter movement) must be inserted directly into the path of the current being measured. Therefore, the **entire ammeter assembly must be connected in series with the load**. The **shunt** itself is a precision, low-resistance resistor. Its purpose is to bypass (shunt) the majority of the circuit current around the sensitive **meter movement** (galvanometer or D'Arsonval movement). Since the shunt must provide an alternate path for the current while keeping the voltage drop across both the shunt and the meter movement equal (which is necessary for correct proportional current division), the shunt must be connected **in parallel with the meter movement**. Thus, the configuration is: the ammeter (shunt + movement) is in series with the load, and the shunt is in parallel with the meter movement. Option B correctly describes the shunt's connection relative to the two components mentioned: **in series with the load** (as part of the overall series ammeter) and **in parallel with the meter movement**. *** ### Why Other Options Are Incorrect **A) in series with the load and in series with the meter movement** If the shunt were in series with the meter movement, it would increase the overall resistance of the ammeter significantly (since resistance adds in series). An ammeter should have extremely low internal resistance to minimize its impact on the measured circuit. Furthermore, connecting them in series would defeat the purpose of the shunt, which is to bypass excess current around the delicate meter movement. **C) in parallel with the load and in series with the meter movement** If the entire ammeter (or just the shunt) were connected in parallel with the load, it would be measuring voltage (acting as a voltmeter), not current. Measuring current requires the device to be in series with the load. Also, placing the shunt in series with the meter movement is incorrect, as explained above. **D) in parallel with the load and in parallel with the meter movement** Connecting the device in parallel with the load (like a voltmeter) is incorrect for current measurement. While connecting the shunt in parallel with the meter movement is correct, the first part of the statement makes the entire option incorrect for describing the proper use of an ammeter shunt in a typical circuit setup.