A \( 21 \, \text{V} \) battery with negligible internal resistance is connected to a cubical network of 12 resistors, ea
**Meter bridge** uses uniform wire of length 1 m, balance length l gives R_unknown = R_known·l/(100-l). Principle same as Wheatstone, with wire resistances proportional to lengths, allowing unknown resistance determination from length ratio. Equivalent resistance: Rₑq = (5/6) R = (5/6) × 2.5 = (12.5/6) ≈ 2.08 Ω . Total current: I = (V/Rₑq) = (21/(12.5/6)) = 21 × (6/12.5) = 10.08 A ≈ 10.1 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 10.1 A,
Ref: NCERT > Physics Book > Current Electricity > Wheatstone Bridge and Meter Bridge