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KVPY Sample Paper KVPY Stream-SX Model Paper-17

  • question_answer
    A particle having the same charge as of electron Moves in a circular path of radius 0.5 cm under the influence of a magnetic field of 0.5 T. If an electric filed of 100 V/m makes it to move in a straight path, then particle is (given charge of electron \[=1.6\times {{10}^{-19}}C\])

    A) \[9.1\times {{10}^{-31}}kg\]     

    B) \[1.6\times {{10}^{-27}}kg\]

    C) \[1.6\times {{10}^{-19}}kg\]     

    D) \[2.0\times {{10}^{-24}}kg\]

    Correct Answer: D

    Solution :

    \[eE=evB\]
    \[\Rightarrow \]   \[E=\left( \frac{eBr}{m} \right)B\]
    \[\Rightarrow \]   \[m=\frac{e{{B}^{2}}r}{E}\]
    \[\Rightarrow \]   \[m=\,\frac{(1.6\times {{10}^{-19}}){{(0.5)}^{2}}\,(0.5\times {{10}^{-\,2}})}{100}\]
                \[=2\times {{10}^{-24}}kg.\]


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