KVPY Sample Paper KVPY Stream-SX Model Paper-23

All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before travelling 1 m in the direction of uniform electric field of 4 N/C. The work function of the surface is:

A) 4 eV

B) 6.2 eV

C) 2 eV

D) 2.2 eV

Correct Answer: D

Solution :

The electron ejected with maximum speed \[{{v}_{\max }}\]are stopped by electric field \[E=4N/C\] after travelling a distance\[~d=1\,m\]

\[\therefore \] \[\frac{1}{2}\,m\,{{V}_{\max }}^{2}=eE\,\,d=4e\,V\]

The energy of incident photon\[=\frac{1240}{200}=6.2\,eV\] From equation of photo electric effect\[\frac{1}{2}m{{v}_{\max }}^{2}=h\upsilon -{{\phi }_{0}}\]

\[\therefore \] \[{{\phi }_{0}}=6.2-4=2.2\,eV.\]

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KVPY Sample Paper KVPY Stream-SX Model Paper-23

question_answer All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before travelling 1 m in the direction of uniform electric field of 4 N/C. The work function of the surface is: A) 4 eV B) 6.2 eV C) 2 eV D) 2.2 eV

All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before travelling 1 m in the direction of uniform electric field of 4 N/C. The work function of the surface is:

A) 4 eV

B) 6.2 eV

C) 2 eV

D) 2.2 eV