Question

Light of wavelength 3500 Å is incident on two metals A and B whose work functions are 4.2 eV and 1.9 eV respectively. Which metal will emit photoelectrons?

Solution

Correct option is

B

     

      

      

The energy of the incident light is 

    

           

  

where  is the Planck’s constant,  is the speed of light in air and  is the charge of electron. Substituting the values of  and solving we get E = 3.55 eV. Photoelectrons will be emitted from a metal if the energy of the incident light is greater than the work function. Since the work function of metal Bis less than E, metal B will emit photoelectrons.  

SIMILAR QUESTIONS

Q1

A metal whose work function is 3.31 eV is illuminated by light ofwavelength . What is the threshold frequency for photoelectric emission? Take  

Q2

What is the maximum energy of photoelectrons emitted from the metal. 

Q3

The photoelectric threshold for a certain metal surface is 330 Å. What is the maximum kinetic energy of photoelectron released, if any, by a radiation of wavelength 1100 Å ? 

Q4

When a point source of light is at a distance of 50 cm from a photoelectric cell, the cut-off voltage is found to be V0. If the same source is placed at a distance of 1 m from the cell, the cut-off voltage will be 

Q5

No photoelectrons are emitted from a metal if the wavelength of light exceeds 6000 Å. The work function of the metal is approximately equal to

Q6

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

Q7

The wavelength in air associated with a photon of energy E is (c is the speed of light in air and h is the Planck’s constant)

Q8

A metal whose work function is 3.3 eV is illuminated by light ofwavelength . What is the threshold frequency for photoelectric emission? Planck’s constant .

Q9

In X-ray tube produces a continuous spectrum of radiation with its short-wavelength end at 0.33 Å. What is the maximum energy of a photon in the radiation? Planck’s constant .

Q10

An ultraviolet light of wavelength 2000 Å irradiates a photocell made of molybdenum metal. If the stopping potential is –1.5 V, what is the work function of the metal? Planck’s constant .