When measuring the resistance of a branch in a parallel curcuit, it is
The correct answer and explanation is:
When measuring the resistance of a branch in a parallel circuit, it is necessary to isolate the branch from the rest of the circuit before taking a resistance measurement.
A parallel circuit is a type of electrical circuit in which components are connected across common points or junctions, providing multiple paths for the current to flow. Each branch in a parallel circuit carries a portion of the total current. When power is applied, the branches interact because current divides based on the resistance of each path.
A multimeter measures resistance by sending a small current through the component and measuring the voltage drop to calculate the resistance using Ohm’s law. If the branch is still connected to other branches, the meter can pick up multiple paths. This causes incorrect readings because the current from the meter can flow through other parts of the circuit, resulting in a resistance measurement that does not represent the branch alone.
Therefore, before measuring the resistance of any single branch in a parallel circuit, the branch must be disconnected at at least one end. This ensures that the only path for the meter’s test current is through the resistor or component of interest. For example, if a resistor is soldered between two points in a circuit board, lifting one leg of the resistor breaks the parallel path and isolates the resistor.
Measuring resistance with the circuit powered on is also unsafe and inaccurate. Any voltage present interferes with the meter’s test current, giving false readings and possibly damaging the meter. Always ensure the power is off and the component is isolated.
Accurate resistance measurement is important for troubleshooting and verifying whether a resistor or branch is within its specified value. Following this procedure helps confirm the health of individual components without misleading results from the interaction of parallel paths.