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  3. RAJASTHAN ­ PET

RAJASTHAN ­ PET Rajasthan PET Solved Paper-2002

  • question_answer
    The potential of illuminate cathode, grid and plate of triode valve are 0, -3 and 80 V respectively. An electron moves with the kinetic energy of 5eV from the surface of cathode. On reaching the grid, the kinetic energy of electron will be

    A)  15 eV           

    B)  2 eV

    C)  85 eV            

    D)  30 eV

    Correct Answer: B

    Solution :

     Grid is at 3 V negative potential w.r.t. cathode hence it will repel electron (negatively charged). Due to this reason, electron will experience a loss of 3 eV in it energy to reach the grid. Hence when it reaches at grid, the KE of electron \[=5\text{ }eV-3\text{ }eV=2\text{ }eV\]


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