COPPER PLATES

This project focuses on the design, construction, and experimental analysis of three distinct meter bridges fabricated using aluminum, steel, and copper base plates. The primary objective was to measure and compare the internal resistance of a constantan wire using these three different conductive materials, and to analyze how the type of base metal affects the accuracy, sensitivity, and stability of resistance measurements. The study is based on the fundamental principle of the Wheatstone Bridge, which provides a reliable method for comparing and determining unknown resistances by achieving a state of balance between two arms of an electrical network. The meter bridge, being a modified form of the Wheatstone bridge, was selected due to its simplicity, accuracy, and wide applicability in electrical measurement laboratories. During fabrication, each meter bridge consisted of a one-meter uniform wire mounted on a polished metal base (aluminum, steel, or copper), fitted with thick brass strips, standard resistors, binding posts, and a jockey for variable contact. A Leclanché cell served as the power source, and a center-zero galvanometer was employed to detect the balance point. Constantan was chosen as the test wire due to its negligible temperature coefficient of resistance and high mechanical stability. Experimental readings were taken for various known resistances, and the corresponding balance lengths were recorded. The internal resistance of the constantan wire was computed and analyzed.