Why should resistance be measured with low currents and voltages?

• A. To avoid heating and changing the resistance you are measuring
• B. To maximize current
• C. To reduce measurement time
• D. To prevent battery drain

Answer: (A)

When measuring resistance, you want the component to stay at a constant temperature, because the resistance can change as it heats up. Pushing more current or higher voltage causes more power to be dissipated as heat (P = I^2R or P = V^2/R). This self-heating changes the material’s temperature and, in turn, its resistance, leading to an inaccurate measurement. Using low currents and voltages minimizes this heating, keeping the temperature stable and giving a more reliable resistance reading. It also reduces the risk of damaging the component or draining a battery.