Question

The work function of cesium atom is 1.9eV . Calculate the thershold wavelength and threshold frequency of radiation.

Answer 1

It is given that the work function (W0) for caesium atom is 1.9 eV.

(a) From the expression,, we get:



Where,

λ0 = threshold wavelength

h = Planck’s constant

c = velocity of radiation

Substituting the values in the given expression of (λ0):



6.53 × 10–7 m

Hence, the threshold wavelengthis 653 nm.
(b) From the expression,, we get:



Where,

ν0 = threshold frequency

h = Planck’s constant

Substituting the values in the given expression of ν0:



(1 eV = 1.602 × 10–19 J)

ν0 = 4.593 × 1014 s–1

Hence, the threshold frequency of radiation (ν0) is 4.593 × 1014 s–1.