Question

Radiation of wavelength 3000 Å falls on a metal surface having work function 2.3 eV. Calculate the maximum speed of ejected electrons.

Answer 1

Data : λ = 3000 Å = 3 × 10^-7 m, 

h = 6.63 × 10^-34 J∙s, 

Φ = 2.3 eV = 2.3 × 1.6 × 10^-19 J, 

c = 3 × 10⁸ m/s, 

m = 9.1 × 10^-31 kg

KE_max = \(\cfrac{hc}\lambda\) - ϕ

KE_max = \(\cfrac12\) mv² max

∴ The maximum speed, V_max