The de-Broglie wavelength $$(\lambda)$$ of a particle is related to its kinetic energy (E) as

Dual nature of light is exhibited by

When radiations of wavelength $$\lambda$$ is incident on a metallic surface the stopping potential required is $$4.8 \mathrm{~V}$$. If same surface is illuminated with radiations of double the wavelength, then required stopping potential becomes $$1.6 \mathrm{~V}$$, then the value of threshold wavelength for the surface is

When a light of wavelength $$300 \mathrm{~nm}$$ fall on a photoelectric emitter, photo electrons are emitted. For another emitter light of wavelength $$600 \mathrm{~nm}$$ is just sufficient for liberating photoelectrons. The ratio of the work function of the two emitters is