CET Karnataka Medical CET - Karnataka Medical Solved Paper-2009

  • question_answer
    An \[\alpha \]-particle of mass 6.4 x 10-27 kg and charge 3.2 x 10-19 C is situated in a uniform electric field of 1.6 x 105 Vm-1. The velocity of the particle at the end of 2 x 10-2 m path when it starts from rest is

    A)  \[2\sqrt{3}\times {{10}^{5}}m{{s}^{-1}}\]  

    B)  \[8\times {{10}^{5}}m{{s}^{-1}}\]

    C)  \[16\times {{10}^{5}}m{{s}^{-1}}\]

    D)  \[4\sqrt{2}\times {{10}^{5}}m{{s}^{-1}}\]

    Correct Answer: D

    Solution :

    Given, \[{{m}_{\alpha }}=6.4\times {{10}^{-27}}kg,\] \[{{q}_{\alpha }}=3.2\times {{10}^{-19}}C,E=1.6\times {{10}^{5}}V{{m}^{-1}}\] Force on \[\text{ }\!\!\alpha\!\!\text{ -}\]particle \[{{q}_{\alpha }}=E=3.2\times {{10}^{-19}}\times 1.6\times {{10}^{5}}\] \[=51.2\times {{10}^{-15}}N\] Now, acceleration of the particle \[\alpha =\frac{F}{{{m}_{\alpha }}}=\frac{51.2\times {{10}^{-15}}}{6.4\times {{10}^{-27}}}\] \[=0.8\times {{10}^{13}}m{{s}^{-2}}\] \[\because \]Initial velocity, u = 0 \[\therefore \] \[{{v}^{2}}=2\alpha S\] \[=2\times 8\times {{10}^{12}}\times 2\times {{10}^{-2}}\] \[=32\times {{10}^{10}}\] or \[v=4\sqrt{2}\times {{10}^{5}}m{{s}^{-1}}\]


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