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JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Cathode Rays and Positive Rays

  • question_answer
    A cathode emits \[1.8\times {{10}^{14}}\] electrons per second, when heated. When 400V is applied to anode all the emitted electrons reach the anode. The charge on electron is \[1.6\times {{10}^{-19}}C\]. The maximum anode current is                [MP PMT 2004]

    A)            \[2.7\mu A\]                        

    B)            \[29\mu A\]

    C)            \[72\mu A\]                         

    D)            29 mA

    Correct Answer: B

    Solution :

                       \[i=\frac{Q}{t}=\frac{ne}{t}=1.8\times {{10}^{14}}\times 1.6\times {{10}^{-19}}=28.8\times {{10}^{-6}}A\]            \[=29\,\mu A\]


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