Practice question

Given: The threshold wavelength of a metal is 550 nm . What is its work function in joules? (Take h = 6.63 × 10⁻³⁴ J s, c = 3 × 10⁸ m/s ) These values define the system as per NCERT data. Formula: v_0 = c/lambda_0 = frac3 × 10⁸⁵⁵⁰ × 10⁻⁹ approx 5.455 × 10¹⁴ Hz. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: phi_0 = h v_0 = 6.63 × 10⁻³⁴ × 5.455 × 10¹⁴ approx 3.617 × 10⁻¹⁹ J . 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.