The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately
Options
(a) 540 nm
(b) 400 nm
(c) 310 nm
(d) 220 nm
Correct Answer:
310 nm
Explanation:
hc / λ(m) = Work function ⇒ λ(max) = hc / w
λ(max) = (6.6 x 10⁻³⁴) × (3 × 10⁸) / (4 × 1.6 × 10⁻¹⁹)
λ(max) = [(6.6 × 3) / (4 × 1.6)] × 10⁻⁷ m
λ(max) = 310 nm