Home
Class 12
PHYSICS
Light of frequency 8.41xx10^(14)Hz is in...

Light of frequency `8.41xx10^(14)Hz` is incident on a metal surface. Electrons with their maximum speed of `7.5xx10^(5)ms^(-1)` are ejected from the surface. Calculate the threshold frequency for photoemission of electrons. Also find the work function of the metal in electron volt `(eV)`. Given Plank's constant `h=6.625xx10^(-34)Js` and mass of the electron `9.1xx10^(-31)kg`.

Text Solution

Verified by Experts

Given `f=8.41xx10^(14)Hz`.
`v=7.5xx10^(5)ms^(-1)`
`v_(0)=?` `omega=?`
`h=6.625xx10^(-34)Js`, `m=9.1xx10^(-31)kg`
Since `E=55.716xx10^(-20)J=5.5716xx10^(-19)J`.
Maximum `KE=(1)/(2)mv^(2)=(1)/(2)xx9.1xx10^(-31)xx(7.5xx10^(5))^(2)`
`=(1)/(2)xx9.1xx56.25xx10^(-21)`
`=255.937xx10^)-21)J`
`(KE)_(max)=2.559xx10^(-19)J`
Using `P.E.` equation, work function `w=hv-(KE)_(max)`
`:.w=hv_(0)=(5.5716-2.559)xx10^(-19)J`
`:.W=` Work fucntion `=hv_(0)=3.0126xx10^(-19)J`
Threshold frequency `v_(0)=(3.0126xx10^(-19))/(6.625xx10^(-34))Hz`
or `v_(0)=0.4547xx10^(15)Hz`
i.e. Threshold frequency `=4.547xx10^(14)Hz`
Work function `=(3.0126xx10^(-19))/(1.6xx10^(-19))=1.883eV`
Work function `=1.883eV`
Promotional Banner

Topper's Solved these Questions

  • ANNUAL EXAMINATION QUESTION PAPER (WITH ANSWER) MARCH 2018

    SUBHASH PUBLICATION|Exercise Part-B|8 Videos

  • ANNUAL EXAM QUESTION PAPER MARCH 2018

    SUBHASH PUBLICATION|Exercise QUESTION|38 Videos

  • ATOMS

    SUBHASH PUBLICATION|Exercise NUMERICALS WITH SOLUTIONS|13 Videos

Similar Questions

Explore conceptually related problems

Light of frequency 7.21 xx 10^(14) Hz is incident on a metal surface. Electrons with a maximum speed of 6.0 xx 10^(5)m//s are ejected from the surface. What is the threshold frequency for photoemission of electrons?

Calculate the wavelength of an electron moving with a velocity of 2.5xx10^(-7) ms^(-1)h=6.626xx10^(-34)Js: mass of an electron= 9.11xx10^(-31) kg.

The deBroglie wavelength of an electron travelling at 1% of the speed of light is( h=6.6xx10^(-4) Js, mass of electron =9.0xx10^(-31) kg

A photon of frequency 1.5xx10^(15) Hz is incident on a metal surface of work function 1.672 eV. Calculate the stopping potential.

The threshold wavelength for the ejection of electron for metal X is 330 nm. The work function for photoelectric emission from metal X is (h=6.6xx10^(-34)Js)

In an atom, an electron is moving with a speed of 6200 m/s which the position of an electron can be locates is (h=6.6xx10^(-34)kgm^(2)s^(-1) , mass of electron e_(m)=9.1xx10^(-31)kg)

When light of frequency 6 xx 10^(14) Hz is incident on a photosensitive metal, the kinetic energy of the photoelectron ejected is 2e V. Calculate the kinetic energy of the photoelectron in eV when light to frequency 5 xx 10^(14) Hz is incident on the same metal. Given Planck's constant, h = 6.625 xx 10^(-34) Js , 1 eV = 1.6 xx 10^(-19) .