A monochromatic light source of frequency v illuminates a metallic surface and ejects photoelectrons. The photoelectrons having maximum energy are just able to ionize the hydrogen atom in ground state. When the whole experiment is repeated with an incident radiation of frequency , the photoelectrons so emitted are able to excite the hydrogen atom beam which then emits a radiation of wavelength 1215Å. Find the work function of the metal and the frequency v


Correct option is

According to Einstein’s photoelectric equation, we have 










Dividing, we get 


On solving : 


                 = 6.875 eV. 

From eq. (i), we have  







The slope of frequency of incident light and stopping  potential for a given  surface will be.


If  is the radsies of the first orbit of hydrogen atom, then the radii of second, third and forth orbit in terms of  us.


Which of the following. Species will produe the shorte wavelength for thetransition  n = 2 to n = ?


The de- Broglie wavelength associated  with proton changes by 0.25%. if its momentum  is changed by the initial momentum was


The ratio of velocities of proton and  - particle is 4:1, then he ratio of their de-brohlie wavelength is


Cut-off wavelength for continous x – rays coming from x – rays tulie operating at 40 kv:


Light of wavelength 400 nm is incident on the cathode of a photocell, the stopping potential recorded is 6.0 V. If the wavelength of the incident light is increased to 600 nm, what will be the new stopping potential? 


When a surface is irradiated with light of wavelength 4950 Å, a photocurrent appears which vanishes if a potential greater than 0.6 V is applied across the photo-table. When a different source of light is used, it is found that the critical retarding potential is changed to 1.1 V. Find the work function of the emitting surface and the wavelength of the second source. If the photoelectrons (after emission from the surface) are subject to a magnetic field of 10 T, what changes will be observed in the above two retarding potentials? 


The maximum kinetic energy of photoelectrons emitted from a certain metallic surface is 30 eV when monochromatic radiation of wavelength  falls on it. When the sane surface is illuminated with light of wavelength , the maximum kinetic energy of photoelectrons is observed to be 10 eV. Calculate the wavelength  and determine the maximum wavelength of incident radiation for which photoelectrons can be emitted by this surface. 


An electron is projected in a uniform electric field in a direction at right angles to the field. The trajectory of the electron will be