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When a surface is irradiated with light ...

When a surface is irradiated with light of wavelength `4950 Å`, a photocurrent appears which vanishes if a retarding potential greater than 0.6 volt is applied across the phototube. When a second source of light is used, it is found that the critical potential is changed to 1.1 volt.
The work- function of the emitting surface is i

A

`2.2eV`

B

`1.5eV`

C

`1.9eV`

D

`1.1eV`

Text Solution

Verified by Experts

The correct Answer is:
C
`E_1 = (12375)/(4950) = 2.5 eV`
`K_1 = maximum kinetic energy = 0.6eV`
`W = E_1 - K_2 = 1.9 eV`.
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