A radiation of energy $E$ falls on a perfectly reflecting surface. The momentum transferred to the surface is (let $c \equiv$ speed of light)

According to the photoelectric effect, the plot of kinetic energy of the emitted photo-electrons from a metal versus the frequency of the incident radiation gives a straight line whose slope

In a photoelectric effect experiment if the frequency of light is doubled, the stopping potential will

A monochromatic light of wavelength $\lambda$ ejects photoelectrons from a metal surface with work function ( $\phi) 2.4 \mathrm{eV}$. These photoelectrons are made to collide with hydrogen atoms in ground state. The maximum value of $\lambda$ for which hydrogen atom may be ionised is [take, $h c=1240 \mathrm{eV}-\mathrm{nm}$ ]