RAJASTHAN PMT Rajasthan - PMT Solved Paper-2000

  • question_answer
    75.      Work function of a metal is \[5.26\text{ }\times {{10}^{-18}}\] then its threshold wavelength will be:

    A)  \[736.7\,\overset{\text{o}}{\mathop{\text{A}}}\,\]      

    B)         \[760.7\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

    C)  \[301\,\overset{\text{o}}{\mathop{\text{A}}}\,\]          

    D)         \[344.4\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

    Correct Answer: D

    Solution :

    Work function \[W=\frac{hc}{\lambda }\] \[\lambda =\frac{hc}{W}\] \[=\frac{6.6\times {{10}^{10-34}}\times 3\times {{10}^{8}}}{5.26\times {{10}^{18}}}=344.4\overset{\text{ }\!\!{}^\circ\!\!\text{ }}{\mathop{\text{A}}}\,\]


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