When the frequency of the incident radiation on a metallic plate is doubled, KE of the photolectrons will be

When light of wavelength $248 \mathrm{nm}$ falls on a metal of threshold energy $3.0 \mathrm{eV}$, the de-Broglie wavelength of emitted electrons is ________ $\mathrm{\AA }$. (Round off to the Nearest Integer).

[Use : $\sqrt{3}=1.73, \mathrm{h}=6.63\times {10}^{-34} \mathrm{Js}; {\mathrm{m}}_{\mathrm{e}}=9.1\times {10}^{-31} \mathrm{kg}; \mathrm{c}=3.0\times {10}^8{ \mathrm{ms}}^{-1}; 1 \mathrm{eV}=1.6\times {10}^{-19} \mathrm{J}]$

What is the work function of the metal if the light of wavelength $4000\mathrm{\AA }$ generates photoelectrons of velocity $6\times {10}^5{\mathrm{ms}}^{-1}$ from it?

(Mass of electron $\mathrm{ }=9\times {10}^{-31} \mathrm{kg}$, velocity of light $=3\times {10}^8 {\mathrm{ms}}^{-1}$, Planck's constant $=6.626\times {10}^{-34} \mathrm{Js}$, Charge of electron $=6.626\times {10}^{-34} \mathrm{Js}$)

The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is:

[Given: The threshold frequency of platinum is $1.3\times {10}^{15}{ \mathrm{s}}^{-1}$ and $\mathrm{h}=6.6\times {10}^{-34}\mathrm{Js}$]

With regard to photoelectric effect, identify the CORRECT statement among the following:

If $\mathrm{p}$ is the momentum of the fastest electron ejected from a metal surface after the irradiation of light having wavelength $\mathrm{\lambda },$ then for $1.5\mathrm{ }\mathrm{p}$ momentum of the photoelectron, the wavelength of the light should be:

(Assume kinetic energy of ejected photoelectron to be very high in comparison to work function)

The photoelectric behaviour of $\mathrm{K}, \mathrm{Li}, \mathrm{Mg}$ and $\mathrm{Ag}$ metals is shown in the plot below. If light of wavelength $400 \mathrm{nm}$ is incident on each of these metals, which of them will emit photoelectrons? [Planck's contant $h=6.626\times {10}^{-34}\mathrm{Js}$; velocity of light $c=3\times {10}^8 {\mathrm{ms}}^{-1}; 1\mathrm{eV}=1.6\times {10}^{-19} \mathrm{J}$]