Final answer:
Tech A and Tech B are both correct; a '+' sign on a voltmeter indicates a higher voltage at the red lead than at the black lead, while a '−' sign signifies a lower voltage at the red lead. Correctly interpreting voltmeter and ammeter readings is essential for circuit analysis.
Step-by-step explanation:
Both Tech A and Tech B are correct in their statements about reading DC voltage on a meter. When a voltmeter shows a "+" sign before a number, it indicates that the voltage at the red lead is higher than at the black lead. Conversely, a "−" sign indicates that the voltage at the red lead is lower compared to the black lead. In terms of circuit measurements, this translates to the red lead being connected to a more positive potential in the circuit, and the black lead being connected to a more negative or ground potential.
It is crucial in electrical measurements to correctly interpret the readings of instruments like voltmeters and ammeters, as these are fundamental for analyzing and understanding the behavior of electrical circuits. This understanding is vital for ensuring that circuits operate properly and safely. Standard measurements can alter the circuit being measured, so precise understanding and correct interpretation of meter readings are essential to reduce uncertainties in electrical measurements.
Using a voltmeter to measure voltage across components like resistors requires that it be connected in parallel with the component, ensuring accurate reading of the potential difference between two points in the circuit.