The energy of a photon of light of wavelength 450 nm is

(1) $4.4\times {10}^{-19} \mathrm{J}$             

(2) $2.5\times {10}^{-19} \mathrm{J}$

(3) $1.25\times {10}^{-17} \mathrm{J}$            

(4) $2.5\times {10}^{-17} \mathrm{J}$

Which of the following is true for photon 
(1) $\mathrm{E}=\frac{\mathrm{hc}}{\mathrm{\lambda }}$         

(2) $\mathrm{E}=\frac{1}{2}{\mathrm{mu}}^2$

(3) $\mathrm{p}=\frac{\mathrm{E}}{2\mathrm{v}}$         

(4) $\mathrm{E}=\frac{1}{2}{\mathrm{mc}}^2$

Einstein's photoelectric equation states that \(E_k=h \nu -\phi.\)${\mathrm{}}_{}$ In this equation \(E_k\) refers to:

Kinetic energy with which the electrons are emitted from the metal surface due to photoelectric effect is 

(1) Independent of the intensity of illumination

(2) Independent of the frequency of light

(3) Inversely proportional to the intensity of illumination

(4) Directly proportional to the intensity of illumination

The threshold wavelength for photoelectric emission from a material is 5200 Å. Photo-electrons will be emitted when this material is illuminated with monochromatic radiation from :

(1) 50-watt infrared lamp

(2) 50-watt ultraviolet lamp

(3) 1-watt ultraviolet lamp

(4) Both (2) and (3)

Threshold frequency for a metal is ${10}^{15}$ Hz. Light of $\mathrm{\lambda }=4000$$\stackrel{0}{\mathrm{A}}$ falls on its surface. Which of the following statements is correct

(1) No photoelectric emission takes place

(2) Photo-electrons come out with zero speed

(3) Photo-electrons come out with ${10}^3$ m/sec speed

(4) Photo-electrons come out with ${10}^5$ m/sec speed

Einstein got Nobel prize on which of the following works

(1) Mass-energy relation

(2) Special theory of relativity

(3) Photoelectric equation

(4) (a) and (b) both

The photo-electrons emitted from a surface of sodium metal are such that 

(1) They all are of the same frequency

(2) They have the same kinetic energy

(3) They have the same de Broglie wavelength

(4) They have their speeds varying from zero to a certain maximum

A metal surface of work function \(1.07\) eV is irradiated with light of wavelength \(332\) nm. The retarding potential required to stop the escape of photo-electrons is:
1. \(4.81\) eV
2. \(3.74\) eV
3. \(2.66\) eV
4. \(1.07\) eV
 

In a photo cell, the photo-electrons emission takes place
(1) After ${10}^{-1}$ sec on incident of light rays

(2) After ${10}^{-3}$ sec on incident of light rays

(3) After ${10}^{-6}$ sec on incident of light rays

(4) After ${10}^{-8}$ sec on incident of light rays