Question

All electrons ejected from a surface by incident light of wavelength 200nm can be stopped before travelling 1m in the direction of uniform electric field of 4N/C. The work function of the surface is(a) 4 eV(b) 6.2 eV(c) 2 eV(d) 2.2 eV

Answer 1

$<b>$

Option D is Correct

Answer 2

Answer:

D) 2.2 eV

Explanation:

E = 4 N/C (Given)

λ = 200 nm = 2×10^-7 m (Given)

d = 1 m (Given)

The kinetic energy gets converted to electric field energy =

1/2 mv² = Ede

1/2 mv² = 4 × 1 × e

1/2 mv² = 4 eV

Incident photon emits energy-

hυ = 12.4×10^-9 / 2×10^-9

hυ = 6.2 eV

Work function of the surface is-

Ф = hυ - 1/2 mv²

Ф = 6.2 - 4

Ф = 2.2 eV

Thus, the work function of the surface is 2.2 eV .