Assuming photoemission to take place, the factor by which the maximum velocity of the emitted photoelectrons changes when the wavelength of the incident radiation is increased four times, is 
(1) 4                       

(2) $\frac{1}{4}$

(3) 2                       

(4) $\frac{1}{2}$

If the work function of a metal is $\text{'}\mathrm{\varphi }\text{'}$ and the frequency of the incident light is '$\nu$', there is no emission of photoelectron if
(1) $\mathrm{v}<\frac{\mathrm{\varphi }}{\mathrm{h}}$                   

(2) $\mathrm{v}=\frac{\mathrm{\varphi }}{\mathrm{h}}$   

(3) $\mathrm{v}>\frac{\mathrm{\varphi }}{\mathrm{h}}$                   

(4) $\mathrm{v}>=\frac{\mathrm{\varphi }}{\mathrm{h}}$   

Light of wavelength $\mathrm{\lambda }$ strikes a photo-sensitive surface and electrons are ejected with kinetic energy E. If the kinetic energy is to be increased to 2E, the wavelength must be changed to $\mathrm{\lambda }\text{'}$ where 
(1) $\mathrm{\lambda }\text{'}=\frac{\mathrm{\lambda }}{2}$           

(2) $\mathrm{\lambda }\text{'}=2\mathrm{\lambda }$

(3) $\frac{\mathrm{\lambda }}{2}<\mathrm{\lambda }\text{'}<\mathrm{\lambda }$      

(4) $\mathrm{\lambda }\text{'}>\mathrm{\lambda }$

The photoelectric work function for a metal surface is 4.125 eV. The cut-off wavelength for this surface is

(1) 4125 Å                 

(2) 2062.5 Å

(3) 3000 Å                 

(4) 6000 Å

As the intensity of incident light increases,

Which of the following is dependent on the intensity of incident radiation in a photoelectric experiment

(1) Work function of the surface

(2) Amount of photoelectric current

(3) Stopping potential

(4) Maximum kinetic energy of photoelectrons

The maximum kinetic energy of photoelectrons emitted from a surface when photons of energy 6 eV fall on it is 4 eV. The stopping potential in volts is

(1) 2                     

(2) 4

(3) 6                     

(4) 10

Work function of a metal is 2.1 eV. Which of the waves of the following wavelengths will be able to emit photoelectrons from its surface ?
(1) 4000 Å, 7500 Å                     

(2) 5500 Å, 6000 Å

(3) 4000 Å, 6000 Å                     

(4) None of these

The cathode of a photoelectric cell is changed such that the work function changes from ${\mathrm{W}}_1$ to ${\mathrm{W}}_2$ $\left({\mathrm{W}}_2>{\mathrm{W}}_1\right)$. If the current before and after the change are ${\mathrm{I}}_1$ and ${\mathrm{I}}_2$, all other conditions remaining unchanged, then (assuming $\mathrm{h\nu }>{\mathrm{W}}_2$) :

(1) ${\mathrm{I}}_1$= ${\mathrm{I}}_2$               

(2) ${\mathrm{I}}_1$< ${\mathrm{I}}_2$

(3) ${\mathrm{I}}_1$>${\mathrm{I}}_2$               

(4) ${\mathrm{I}}_1<{\mathrm{I}}_2<2{\mathrm{I}}_1$