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Wave property of electrons implies that ...

Wave property of electrons implies that they will show diffraction effects. Davission and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure)

The surface of a metal is 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

1000 V

B

2000 V

C

50 V

D

500 V

Text Solution

Verified by Experts

The correct Answer is:
C
`Deltalamda= 2d sin theta`
`implies i =30^@ , d = 1 Å , theta = 60 ^@`
for , n =1
`nlamda =2d sin theta `
`lamda=2dsin(90-i)=2xx1Åxxsin60^@`
`lamda=sqrt3Å`
Form de Broglie `lamda=(12.27)/(sqrtV)Å`
`V=((12.27)/lamda)^2=((12.27)/(sqrt3Å))`
`V=50V`
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