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  • Solve it, Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. Then the ratio of the wavelengths is nearest to

Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. Then the ratio of the wavelengths is nearest to

Option 1)

1 : 2

 Option 2)

4 : 1
Option 3)

2 : 1

 Option 4)

1 : 4

Answers (1)

best_answer

As we learnt in

Work function -

Energy used to overcome the surface barrier and come out of metal surface.

\phi = h\nu _{0}

- wherein

h= Plank's \: constant

\nu _{0}= threshold \: frequency

 

 For electron to be ejected \frac{hc}{\lambda}={\phi}

Ratio of wavelength =\frac{h_{2}}{\lambda_{1}}=\frac{\phi_{1}}{\phi_{2}}

=\frac{\lambda_{sod}}{\lambda_{copp}}=\frac{\phi_{copper}}{\phi_{sodium}}=\frac{4.5}{2.3}\simeq2

Correct answer is 3


Option 1)

1 : 2

This is an incorrect option.

Option 2)

4 : 1

This is an incorrect option.

Option 3)

2 : 1

This is the correct option.

Option 4)

1 : 4

This is an incorrect option.

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