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NEET Sample Paper NEET Sample Test Paper-49

  • question_answer
    A and B are two metals with threshold frequencies \[1.8\,\,\times \,\,{{10}^{14}}\] Hz and \[2.2\,\,\times \,\,{{10}^{14}}\] Hz. Two identical photons of energy 0.825 eV each are incident on them. Then photoelectrons are emitted from -

    A) B alone            

    B) A alone

    C) Neither A nor B

    D) Both A & B

    Correct Answer: B

    Solution :

    \[{{w}_{A}}=\frac{6.6\times {{10}^{-34}}\,\times 1.8\times {{10}^{14}}}{1.6\times {{10}^{-19}}}\,=\,0.74\,\,eV\]\[{{w}_{B}}=\frac{6.6\times {{10}^{-34}}\,\times 2.2\times {{10}^{14}}}{1.6\times {{10}^{-19}}}\,=\,0.91\,\,eV\] \[\therefore \] photoelectrons will emit from A alone


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