The work function of a certain metal surface Si is ϕ. The surface is illuminated by monochromatic light of wavelength λ and the speed of the most energetic electron emitted is found to be v. Now another metal surface S2 with half the work function as that of S1 is illuminated with another monochromatic light having wavelength 2λ and the speed of the most energetic electron emitted in this case is found to be kv. The value of k2 is -
1
1
2
\(\frac{1}{\sqrt{2}}\)
3
\(\frac{1}{2}\)
4
2