Home
Class 12
PHYSICS
Consider a metal exposed to light of wav...

Consider a metal exposed to light of wavelength 600nm. The maximum energy of the electrons doubles when light of wavelength 400nm is used. Find the work function in eV.

Text Solution

Verified by Experts

Give , wavelength of light used initially ,
`lamda= 600 nm `
Let `K_(max)` be the maximum energy of electron for `lamda_1` .
For `lamda.= 400 nm,`
`K._(max)=2K_(max)`
Also, `K_(max)=hv-phi_(0)=((hc)/(lamda))-phi_0" "....(i)`
and `K._(max)=2K_(max)=((hc)/(lamda.))-phi_0" "...(ii)`
where `phi_0` is the work function of metal
Dividing (ii) by (i) , we have
`2=((hc//lamda.)-phi_0)/((hc//lamda)-phi_0)`
`implies(2hc)/lamda-2phi_0=(hc)/(lamda.)-phi_0`
`implieshc(2/lamda-1/(lamda.))=phi_0`
Then `phi_0=1240(2/600-1/400)=eV=1.03eV`
Promotional Banner

Topper's Solved these Questions

  • DUAL NATURE OF RADIATION AND MATTER

    MODERN PUBLICATION|Exercise Higher Order Thinking Skills & Advanced Level (QUESTIONS WITH ANSWERS)|8 Videos

  • DUAL NATURE OF RADIATION AND MATTER

    MODERN PUBLICATION|Exercise Revision Exercises (Very Short Answer Questions)|45 Videos

  • DUAL NATURE OF RADIATION AND MATTER

    MODERN PUBLICATION|Exercise NCERT FILE (NCERT - Exemplar Problems - Subjective Questions (Very Short Answer Type Questions))|5 Videos

  • CURRENT ELECTRICITY

    MODERN PUBLICATION|Exercise Chapter Practice Test|15 Videos

  • ELECTRIC CHARGES AND FIELDS

    MODERN PUBLICATION|Exercise Chapter Practice Test|15 Videos

Similar Questions

Explore conceptually related problems

A light of wavelength 600 nm is incident on a metal surface. When light of wavelength 400 nm is incident, the maximum kinetic energy of the emitted photoelectrons is doubled. The work function of the metals is

The surface of a metal is illuminated with light of wavelength 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. What is the work function of the metal ? [ hC=1240 eV*nm ]

Find the maximum magnitude of the linear momentum of a photoelectron emitted when light of wavelength 400 nm falls on a metal having work function 2.5e V.

If a metal is exposed with light of wavelength lambda, the maximum kinetic energy produced is found to be 2 eV. When the same metal is exposed to a wavelength (lambda)/(5) the maximum kinetic energy was found to be 14 eV. Find the value of work function (in eV).

The photoelectric work function of a metal is 3 eV . The maximum kinetic energy of the emitted electrons when light of wavelength 3000 Å falls on it is

Lithium has a work function of 2.3eV . It is exposed to light of wavelength 4800Å . Find the maximum kinetic energy with which electron leaves the surface. What is the longest wavelength which can produce the photoelectrons?

When a metal surface is illuminated by light wavelengths 400 nm and 250 nm , the maximum velocities of the photoelectrons ejected are upsilon and 2 v respectively . The work function of the metal is ( h = "Planck's constant" , c = "velocity of light in air" )

Light of wavelength 1824 Å , incident on the surface of a metal , produces photo - electrons with maximum energy 5.3 eV . When light of wavelength 1216 Å is used , maximum energy of photoelectrons is 8.7 eV . The work function of the metal surface is