Question

If the work function of a metal is 3 eV, calculate the threshold wavelength of that metal.
(Velocity of light = 3 x 10⁸ m/s, Planck’s constant = 6.63 x 10^–34 J.s.; 1 eV = 1.6 x 10^–19 J)

Answer 1

Given: W0 = 3eV = 3 x1.6 x 10^-19
= 4.8 x 10^-19 J,
h = 6.63x 10^-34 J – s,
e = 1.6 x 10^-19 C,
c = 3 x 10⁸ m/s,

To find: Threshold wavelength (λ₀),

`lambda_0=(hc)/W_0`

`=(6.63xx10^-34xx3xx10^8)/(4.8xx10^-19)`

`lambda_0=4.14 xx 10^-7 m`

Threshold wavelength of the metal is 4.14 x 10^–7 m.