Resistance Of A Galvanometer By Half Deflection Method

Resistance Of A Galvanometer By Half Deflection Method — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.

Resistance of a Galvanometer by Half-Deflection Method Used in experimental physics to determine the internal resistance of a galvanometer using a DC source, a high resistance box, and a shunt resistance box. Initial current I = E / (R + G) produces deflection theta. When shunt S is connected, effective resistance becomes R + (GS / (G + S)). Current through galvanometer becomes I' = [E / (R + (GS / (G + S)))] [S / (G + S)]. Condition for half-deflection: I' = I / 2. Solving the equation [E S / (R(G + S) + GS)] = E / [2(R + G)] leads to G = RS / (R - S). The value of R must be significantly larger than G to keep the initial current within the galvanometer's range. The EMF of the battery must remain constant throughout the experiment. The resistance of the connecting wires is assumed to be negligible. Thinking G is equal to S; G is only approximately equal to S if R is infinitely large. Forgetting that R must be connected in series and S in parallel. Assuming this formula works for AC circuits without considering reactance.