Which instrument is placed at the center of a Wheatstone bridge?
Galvanometer placed at center of Wheatstone bridge to detect null.
Ref: NCERT Physics Class 12 Chapter 3 Current Electricity
#bridge balance
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In a Wheatstone bridge, what is the condition for no current to flow through the galvanometer?
**Wheatstone bridge balance** condition R₁/R₂ = R₃/R₄, R₄ = R₂ R₃/R₁, when galvanometer current zero, potentials at midpoints equal. At balance, no current through galvanometer, enabling precise resistance measurement independent of source voltage. No current flows when the bridge is balanced, i.e., R₁ / R₂ = R₃ / R₄ , making the potentials at the galvanometer’s nodes equal, so the potential difference across it is zero. 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 = I²R, evaluation yields Ratio of resistances in opposite a
Ref: NCERT > Physics Book > Current Electricity > Wheatstone Bridge and Meter Bridge
A Wheatstone bridge with \( R_1 = 9 \, \Omega \), \( R_2 = 18 \, \Omega \), \( R_3 = 12 \, \Omega \), \( R_4 = 24 \, \Om
**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. Check balance: (R₁/R₂) = (9/18) = 0.5 , (R₃/R₄) = (12/24) = 0.5 . Bridge is balanced. Since balanced, I_g = 0 A . 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 = I²R, evaluation yields 0 A,
Ref: NCERT > Physics Book > Current Electricity > Wheatstone Bridge and Meter Bridge
