notesonly.in

Light of 6 × 10¹⁴ Hz shines on metal with threshold 4 × 10¹⁴ Hz. Find max KE of ejected electrons. Step 1: KE_max = h(ν − ν₀) = 6.626 × 10⁻³⁴ × (6 − 4) × 10¹⁴. Step 2: = 6.626 × 10⁻³⁴ × 2 × 10¹⁴ = 1.325 × 10⁻¹⁹ J. Step 3: In eV: ÷ 1.6 × 10⁻¹⁹ ≈ 0.83 eV. Below threshold frequency, NO electrons emerge — however bright the light.