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When ultraviolet radiation of a certain ...

When ultraviolet radiation of a certain frequency falls on a potassium target, the photoelectrons released can be stopped completely by a retarding potential of 0.6 V. If the frequency of the radiation is increased by 10%, this stopping potential rises to 0.9 V. The work function of potassium is

A

2.0 eV

B

2.4 eV

C

3.0 eV

D

2.8 eV

Text Solution

Verified by Experts

The correct Answer is:
B
`KE_("max") =exxV_0`
`= exx0.6 = 0.6 eV`
Einstein photoelectric equation
`(KE)_("max") = hf -phi`
`implies E=hf =0.6phi" "...(i)`
`(KE_("max"))= exxV_0= exx0.9 = 0.9eV`
`1.1 E = 0.9 +phi`
By eq. `(ii)/(i) ,implies 1.1 = (0.9 +phi)/(0.6+phi)impliesphi=2.4eV`
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