The work function of a metal surface is 4eV . The longest wavelength of light that can cause photoelectron emission from this surface is approximately

Question

The work function of a metal surface is 4eV . The longest wavelength of light that can cause photoelectron emission from this surface is approximately (A) 540 nm (B) 400nm (C) 310nm (D) 220 nm

Tardigrade Admin · Accepted Answer

Let &lambda;m = Longest wavelength of light (h c/(λ )m)=φ( textwork function) Therefore, λ m=(h c/φ)=(6 .63 × 10- 34 × 3 × 108/4 .0 × 1 .6 × 10- 19) Or &lambda;m = 310 nm.

Q. The work function of a metal surface is $4 e V$ . The longest wavelength of light that can cause photoelectron emission from this surface is approximately

$540 nm$

$400 nm$

$310 nm$

$220 nm$

Let λ_m = Longest wavelength of light
$\frac{h c}{( λ ) _{m}} = ϕ (work function)$
Therefore, $λ_{m} = \frac{h c}{ϕ} = \frac{6.63 \times 1 0 ^{- 34} \times 3 \times 1 0 ^{8}}{4.0 \times 1.6 \times 1 0 ^{- 19}}$
Or λ_m = 310 nm.

Q. The work function of a metal surface is 4eV . The longest wavelength of light that can cause photoelectron emission from this surface is approximately

540nm

400nm

310nm

220nm