JEE Main & Advanced Physics Electrostatics & Capacitance NEET PYQ - Electrostatics and Capacitance

  • question_answer
    A bullet of mass 2g is having a charge of \[2\,\mu C\]. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s?               [AIPMT (S) 2004]

    A) 5 kV

    B) 50 kV

    C) 5 V

    D) 50 V

    Correct Answer: B

    Solution :

    [b] Key Idea: When bullet of mass m and charge q is accelerated through potential difference of V volt, then it attains a kinetic energy equal to qV.
    Kinetic energy of bullet \[=qV\]
    i.e.,       \[\frac{1}{2}m{{v}^{2}}=qV\]
    \[\Rightarrow \]   \[V=\frac{m{{v}^{2}}}{2q}\]
    Given,   \[m=2g=2\times {{10}^{-3}}kg,\,\,v=10\,m/s,\]
    \[q=2\mu \,C=2\times {{10}^{-6}}C\]
    Substituting the values in relation for V, we obtain
    \[V=\frac{2\times {{10}^{-3}}\times {{(10)}^{2}}}{2\times 2\times {{10}^{-6}}}\]
    \[=50\times {{10}^{3}}\,V\,=\,50\,kV\]


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