KVPY Sample Paper KVPY Stream-SX Model Paper-17

The magnetic filed associated with a light wave is given, at b by \[B={{B}_{0}}[\sin (3.14\times {{10}^{7}})ct+\sin \,(6.28\times {{10}^{7}})ct]\]. If this light falls on a silver plate having a work function of 4.7 eV, what will be the maximum kinetic energy of the photo electrons?

A) 6.82e V

B) 12.5e V

C) \[6.25\times {{10}^{5}}\]

D) \[4.87\times {{10}^{5}}\]

Correct Answer: D

Solution :

\[K{{E}_{Max}}=h{{v}_{Max}}-\phi \]

\[=\frac{(6.6\times {{10}^{-34}})\,(6.28\times {{10}^{7}})(3\times {{10}^{8}})}{1.6\times {{10}^{-19}}\times 2\times 3.14}-4.7\]

\[=12.37-4.7\]\[=7.67\text{ }eV.\]