Practice question

**Unbalanced bridge** has potential difference between galvanometer nodes, current direction determined by which node higher potential, i.e., if R₁/R₂ > R₃/R₄, left node higher, current flows one way, else opposite. Galvanometer deflection indicates imbalance magnitude. At balance, the potential at the two junctions connected to the galvanometer is equal (due to the ratio condition R₁ / R₂ = R₃ / R₄ ), so the potential difference across the galvanometer is zero, and no current flows through it. Applying I = n e A v_d, R = ρ l/A, R_t = R₀[1+αΔT], Kirchhoff's ΣI=0, ΣV=0, R_eq series/parallel, V = ε - I r and P =