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A metal is illumimated by light of two d...

A metal is illumimated by light of two different wavelength `248nm` and `310 nm` . The maximum speeds of the photoelectrons corresponding in these wavelength are `u_(1) and u_(2)` respectively . If the ratio `u_(1) : u_(2) = 2 : 1` and `hc = 1240 eVnm `, the work function of the meal is nearly

A

`3.7 eV`

B

`3.2 eV`

C

`2.8 eV`

D

`2.8 eV`

Text Solution

Verified by Experts

The correct Answer is:
A
`248 nm 1240//248 eV =5eV`
`310 nm 1250//310 eV = 4eV`
`(KE_(1))/(KE_(2))=(4)/(1) =(5ev-W)/(4ev-W)`
`rArr 16-4 W =S-W rArr 11 = 3W`
`rArr W = (11)/(3)=3.67 ev 3.7 ev`
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Knowledge Check

  • A metal is illumimated by light of two different wavelength 248nm and 310 nm . The maximum speeds of the photoelecrtron corresponding in these wavwlength are u_(1) and u_(2) respectively . If the ratio u_(1) : u_(2) = 2 : 1 and hc = 1240 eVnm , the work function of the inetial is rearly

    A
    `3.7 eV`
    B
    `3.2 eV`
    C
    `2.8eV`
    D
    `2.5 eV`

  • A metal surface is illuminated by light of two different wavelengths 248 nm and 310 nm. The maximum speeds of the photoelectrons corresponding to these wavelengths are u_1 and u_2 respectively . If the ratio (u_1)/(u_(2))=2/1 and hc = 1240 eVnm , the work function of the metal is nearly .

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

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    `2 hc xx 10 ^(6) J`
    B
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