JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Motion of Charged Particle In Magnetic Field

  • question_answer
    A proton (mass m and charge +e) and an \[\alpha -\]particle (mass 4m and charge +2e) are projected with the same kinetic energy at right angles to the uniform magnetic field. Which one of the following statements will be true                    [NCERT 1983]

    A)            The \[\alpha -\]particle will be bent in a circular path with a small radius that for the proton

    B)            The radius of the path of the \[\alpha -\]particle will be greater than that of the proton

    C)            The \[\alpha -\]particle and the proton will be bent in a circular path with the same radius

    D)            The \[\alpha -\]particle and the proton will go through the field in a straight line

    Correct Answer: C

    Solution :

                       \[r=\frac{\sqrt{2mK}}{qB}i.e.\ r\propto \frac{\sqrt{m}}{q}\] Here kinetic energy K and B are same. \[\therefore \frac{{{r}_{p}}}{{{r}_{\alpha }}}=\frac{\sqrt{{{m}_{p}}}}{\sqrt{{{m}_{\alpha }}}}.\frac{{{q}_{\alpha }}}{{{q}_{p}}}=\frac{\sqrt{{{m}_{p}}}}{\sqrt{4{{m}_{p}}}}.\frac{2{{q}_{p}}}{{{q}_{p}}}=1\]


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