In nickel-cadmium batteries, a rise in cell temperature causes what change in internal resistance?

• A. An increase
• B. A decrease
• C. No change
• D. Unpredictable fluctuation

Answer: (B)

Rising temperature speeds up the chemical reactions inside a nickel-cadmium cell and lets ions move more easily. Internal resistance comes from the electrolyte, contact resistances, and polarization (the buildup of reaction products near the electrodes). When temperature increases, the electrolyte becomes more conductive and electrode kinetics improve, which reduces polarization and lowers the overall resistance. So, internal resistance decreases as temperature rises.