All electrons ejected from a metallic surface by incident light of wavelength (400 ~nm ) travelled (1 ~m ) in the direction of uniform electric field of (2 NC ⁻¹ ) and came to rest. The work function of the surface is

Step-by-step solution

Given, wavelength of incident radiation, ( =400 ~nm =4 10⁻⁷ ~m ) electric field, (E=2 ~N / C ) and distance, (s=1 ~m ) ( ) Energy of the incident light, ( aligned E & = h c = 6.6 10⁻³⁴ 3 10^8 4 10⁻⁷ & =4.95 10⁻¹⁹ ~J = 4.95 10¹⁹ 1.6 10⁻¹⁹ ~J & =3.09 3 leV aligned ) If (a ) be the retardation of emitted electrons in the electric field, then, ( a= q E m ) initial speed (u ) of emitted electron is calculated as (v^2=u^2-2 a s 0=u^2-2 a 1 u^2=2 a= 2 q E m ) ( ) Maximum kinetic energy of the electron, ( aligned & K_ = 1