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The threshold wavelength of a photosensi...

The threshold wavelength of a photosensitive metal is 662.5 nm. If this metal is irradiated with a radiation of wavelength 331.3 nm, find the maximum kinetic energy of the photoelectrons. If the wavelength of radiation is increased to 496.5 nm, calculate the change in maximum kinetic energy of the photoelectrons. (Planck's constant `h = 6.625 xx 10^(-34)` Js and `"speed of light in vacuum" = 3 xx 10^(8)ms^(-1)`)

Text Solution

Verified by Experts

`K.E. =(hc)/(lambda) =(hc)/(lambda_(0))= hc[(1)/(lambda)-(1)/(lambda_(0))]`
Substituting for `lambda = lambda_(1) = 331.3 nm` and `lambda_(0) = 662.5 nm`
We get `KE_(1) = 3 xx 10^(-19)J`
`KE_(2) - KE_(1) = hc[(1)/(lambda_(1))-(1)/(lambda_(0))]`
`lambda_(1) = 331.3 nm` and `lambda_(2) = 496.5 nm`
`KE_(2) -KE_(1) = 2 xx 10^(-19)J`
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The threshold wavelength of a photosensitive metal is 662.5 nm. If this metal is irradiated with a radiation of wavelength 331.3 nm, find the maximum kinetic energy of the photoelectrons. If the wavelength of radiation is increased to 496.5 nm, calculate the change in maximum kinetic energy of the photoelectrons. (Planck's constant h=6.625xx10^(-34) Js and speed of light in vacuum = 3xx10^8 ms^(-1) )

For a metal the maximum wavelength required for photoelectron emission is 340 nm, find the work function. If the radiation of wavelength 250 nm falls on the surface of the given metal. Find the maximum kinetic energy of emitted photo electrons in eV. Given Planck's constant = 6.625 xx 10^(-34) Js , velocity of light in vacuum is 3 xx 10^(8)ms^(-1) .

Knowledge Check

  • Calculate the energy in joule corresponding to light of wavelength 45 nm: (planck's constant h = 6.63 xx 10^-34 Js , speed of light c = 3 xx 10^8ms^-1)

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    `6.67 xx 10^15`
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    `6.67 xx 10^11`
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    `4.42 xx 10^-15`
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    `4.42 xx 10^-18`

  • Light of wavelength 4700Å is incident on a metal plate whose work function is 2 eV. Then maximum kinetic energy of the emitted photoelectron would be

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  • A P - type semiconductor has acceptor level 57 meV above the valence band. The maximum wavelength of light required to create a hole is (Planck's constant h=6.6 xx10^(-34) J-s )

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