VITEEE 2017 Paper

Given : work function § of metal = 2.28 eV
Wavelength of light X = 500 nm = 500 x 109 m
KEmax =

hc

λ

- Φ
KEmax =

6.6×10−34×3×108

5×10−7

- 2.82
KEmax = 2.48 - 2.28 = 0.2 eV
λmin =

h

p

=

h

√2m(KEmax)

=
λmin =

25

9

× 10−9
= 2.80 × 10−9 nm
∴ λ ≥ 2.8 × 10−9 m