Work function (W₀ ) values of six metals (in eV ) are given below. Li Mg Cu Ag K Na array llllll 2.42 & 3.7 & 4.8 & 4.3 & 2.25 & 2.3 array How many of the above metals do not eject the electrons when they are made to strike with radiation of wavelength 400 ~nm ? (h=6.62 10⁻³⁴ Js )

Step-by-step solution

Energy of radiation of wavelength 400 ~nm aligned & ( nm =10⁻⁹ ~m ) & E= h c = 6.6 10⁻³⁴ Js 3.0 10^8 ~ms ⁻¹ 400 10⁻⁹ ~m & =4.95 10⁻¹⁹ ~J & aligned Now, 1 eV =1.6 10⁻¹⁹ ~J aligned E & = 4.95 10⁻¹⁹ 1.6 10⁻¹⁹ & =3.09 eV aligned Since, work function of three metals Mg , Cu and Ag is larger than 3.09 eV , so these metals will not eject electrons on striking with radiation of wavelength 400 ~nm .