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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`]

A

3.09 eV

B

1.41 eV

C

1.51 eV

D

1.68 eV

Text Solution

Verified by Experts

The correct Answer is:
B
According to Einstein's photoelectric equation,
`(K.E.)_("max")=hv-W_(0)` (where `W_(0)` is the work function)
`=(hC)/(lambda)-W_(0)`
`:.W_(0)=(hC)/(lambda)-K_("max")`
`=(1240)/(400)-1.68=3.1-1.68=1.42eV`
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Knowledge Check

  • The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photo electrons was found to be 1.68 eV. The work function of the metal is (h_(c)=1240eV.nm)

    A
    1.41 eV
    B
    1.51eV
    C
    1.68eV
    D
    3.09 eV

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    A
    `1.51 eV`
    B
    `1.68 eV`
    C
    `3.09 eV`
    D
    `1.42 eV`

  • The surface of a metal illuminated with the light of 400 nm . The kinetic energy of the ejected photoelectrons was found to be 1.68 eV . The work function of the metal is : (hc=1240 eV.nm)

    A
    `1.41 eV`
    B
    `1.51 eV`
    C
    `1.68 eV`
    D
    `3.09 eV`

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