NEET Sample Paper NEET Sample Test Paper-21

  • question_answer
    The width of depletion region in p-n junction diode is 500 nm and an internal electric field of \[6\times {{10}^{5}}\,V{{m}^{-1}}\]is also found to exist in it. What is the kinetic energy which a conduction electron must have in order to diffuse from the \[n-\]side to \[p-\]side?

    A)  0.03 eV                      

    B)  0.30 eV          

    C)    0.45 eV          

    D)    0.60 eV

    Correct Answer: B

    Solution :

    Here, \[E=6\times {{10}^{5}}\,V{{m}^{-1}};\,d=500\times {{10}^{-9}}\,m\] Here, height of potential barrier, \[{{V}_{B}}=Ed=6\times {{10}^{5}}\times 500\times {{10}^{-9}}=0.30\,V\] Maximum K.E. of and electron to cross the potential barrier \[=e{{V}_{B}}=e\times (0.30\,V)=0.30\,eV.\] Hence, the correction option is (b).

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