A metal has a work function of 6.6 eV. Which wavelength of incident radiation will NOT cause photoelectric emission? Take h = 6.6 × 10⁻³⁴ J·s and c ≈ 3 × 10⁸ m·s⁻¹.
Options

Question

A metal has a work function of 6.6 eV. Which wavelength of incident radiation will NOT cause photoelectric emission? Take h = 6.6 × 10⁻³⁴ J·s and c ≈ 3 × 10⁸ m·s⁻¹.

G1 Physics · Accepted Answer

Step 1: Photoelectric emission requires photon energy hc/λ ≥ work function W₀. Step 2: Calculate W₀ = 6.6 eV = 6.6 × 1.6 × 10⁻¹⁹ = 1.056 × 10⁻¹⁸ J. Step 3: Threshold wavelength λ₀ = hc/W₀ = (6.6 × 10⁻³⁴ × 3 × 10⁸)/(1.056 × 10⁻¹⁸) = 1.875 × 10⁻⁷ m ≈ 187.5 nm. Step 4: Emission occurs when λ ≤ λ₀. Among the options, only 200 nm exceeds λ₀. Final answer: 200 nm (Option A).