Practice question

Given: A soap film supports 2.0 × 10⁻² N over a 40 cm slider. What is the surface tension? These values define the system as per NCERT data. Formula: S = F/2 l. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: F = 2.0 × 10⁻² N, l = 0.4 m . S = frac2.0 × 10⁻²² × 0.4 = 0.025 N/m . 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.