Practice question

Given: A circular loop of radius 18 cm is deformed into a straight wire in a 0.14 T field in 0.7 s. What is the induced emf? These values define the system as per NCERT data. Formula: Initial flux: Phi = B A = 0.14 × π × (0.18)² = 0.01425 Wb. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Final flux = 0. varepsilon = Δ Phi/Δ t = 0.01425/0.7 = 0.02036 V approx 0.02 V . 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.