Question

Ejection of photoelectrons from metal can be stopped by applying 0.5 v when

Answer 1

Photoelectric Effect -

\frac{1}{2}mu^{2}= hv-hv_{0}

- wherein

where

m is the mass of the electron

u is the velocity associated with the ejected electron.

h is plank’s constant.

v is frequency of photon,

v0 is threshold frequency of metal.

\lambda = 250 nm = 2500\AA

E =\frac{hc}{\lambda }=\frac{12400}{2500}=4.96eV

K\cdot E\cdot = ltopping potential = 0.5 eV

E=W_{0}+K\cdot E\cdot

4.96=W_{0}+0.5

W_{0}= 4.46eV \approx 4.5eV

Option 1)

4 eV

Option 2)

4.5 eV

Option 3)

5 eV

Option 4)

5.5 eV