Questions in Dual Nature of Radiation and Matter

Select	Question
	The work function of aluminium is 4.2 $eV.$ If two photons, each of energy 3.5 $eV$strike an electron of aluminium, then emission of electrons will be
	In photoelectric effect if the intensity of light is doubled then maximum kinetic energy of photoelectrons will become
	Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000 Å falls on the surface, the velocity of the fastest electron ejected from the surface will be
	Mercury violet light $(\lambda = 4558{\AA})$ is falling on a photosensitive material $(\varphi = 2.5eV)$. The speed of the ejected electrons is in $m{s^{ - 1}}$, about
	The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies $f$ and $2f$ are incident on the surfaces of A and B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B)
	Light of frequency $\nu$ is incident on a substance of threshold frequency $\nu _0(\nu _0 < \nu)$. The energy of the emitted photo-electron will be
	The stopping potential $({V_0})$
	If work function of metal is 3$eV$ then threshold wavelength will be
	When wavelength of incident photon is decreased then
	Quantam nature of light is explained by which of the following phenomenon