NEET Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव NEET PYQ-Magnetic Effects Of Current

  • question_answer
    An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field B, at the centre of the circle. The radius of the circle is proportional to:                                                                                    [AIPMT (S) 2005]

    A)  \[\frac{B}{v}\] 

    B)                   \[\frac{v}{B}\]

    C)       \[\sqrt{\frac{v}{B}}\]   

    D)                   \[\sqrt{\frac{B}{v}}\]

    Correct Answer: C

    Solution :

    [c] The time period of electron moving in a circular orbit                         \[T=\frac{\text{circumference}\,\text{of}\,\text{circular}\,\text{path}}{\text{speed}}\]                         \[=\frac{2\pi r}{v}\]             and equivalent current due to electron flow                         \[I=\frac{e}{T}=\frac{e}{(2\pi r/v)}=\frac{ev}{2\pi r}\]             Magnetic field at centre of circle                         \[B=\frac{{{\mu }_{0}}I}{2r}=\frac{{{\mu }_{0}}ev}{4\pi {{r}^{2}}}\]             \[\Rightarrow \]   \[r\,\propto \,\,\sqrt{\frac{v}{B}}\]


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