Umakant Kondapure, Collin Fernandes, Nipun Bhatia, Vikram Bathula and, Ketki Deshpande Solutions for Chapter: Electrons and Photons, Exercise 3: Competitive Thinking

The threshold wavelength for lithium is $5250 \stackrel{\circ }{\mathrm{A}}$. For photoemission to take place, the wavelength of the incident light must be

Photoelectric emission is observed from a metallic surface for frequencies $v_1$ and $v_2$ of the incident light rays $\left(v_1>v_2\right).$ If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of $1:\mathrm{K}$ then the threshold frequency of the metallic surface is 

 

A photoelectric surface is illuminated successively by monochromatic light of wavelength $\lambda$ and $\frac{\lambda }{2}.$ If the maximum kinetic energy of the emitted photoelectrons in the second case is $3$ times that in the first case, the work function of the surface of the material is:$(h = \mathrm{Planck}\text{'}\mathrm{s} \mathrm{constant},c= \mathrm{speed} \mathrm{of} \mathrm{light} )$
 

Two identical photo-cathodes receive the light of frequencies $f_1$ and $f_2.$ If the velocities of the photoelectrons (of mass $m$ ) coming out are $v_1$ $v_2$and $v_2$ respectively, then 
 

The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement?                                                                                                                                                                                             

Light of wavelength ${\lambda }_{\mathrm{A}}$and ${\lambda }_{\mathrm{B}}$ Falls on two identical metal plates $A$ and $B$ respectively. The maximum kinetic energy of photoelectrons is ${\mathrm{K}}_{\mathrm{A}}$ and $K_B$ Respectively, then which one of the following relations is true? $\left({\lambda }_{\mathrm{A}}=2{\lambda }_{\mathrm{B}}\right)$ 
 

The energy of the em waves is of the order of $15 \mathrm{keV}.$ To which part of the spectrum does it belong ?
 

Relation between the stopping potential ${\mathrm{V}}_0$ of a metal and the maximum velocity of the photoelectrons is