Practice question

Given: In a Wheatstone bridge, R_1 = 20 Ω, R_2 = 40 Ω, R_3 = 10 Ω . What should R_4 be for the bridge to be balanced? These values define the system as per NCERT data. Formula: Balance condition: R_1/R_2 = R_3/R_4. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substitute: 20/40 = 10/R_4 . Solve: 0.5 = 10/R_4 Rightarrow R_4 = 10/0.5 = 20 Ω . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.