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NEET Sample Paper NEET Sample Test Paper-43

  • question_answer
    The following figure shows a conducting disc rotating about its axis in a perpendicular magnetic field B. The resistor of resistance R is connected between the centre and the rim. The current in the resistor is - (The radius of the disc is 5.0 cm, angular speed\[\omega =100\]radian/sec., (\[B=0.40\,T\]and\[R=10\Omega .\])

    A) 0.5A                            

    B) 0.2A

    C) 0.3A                            

    D) 0.9A

    Correct Answer: A

    Solution :

    Emf induced between centre and circum \[\varepsilon \,=\frac{B\omega {{a}^{2}}}{2},a\to radius\] \[\therefore \,\,i=\frac{\varepsilon }{R}=\frac{B\omega {{a}^{2}}}{2R}\] \[=\frac{0.4\times 10\times {{(5\times {{10}^{-2}})}^{2}}}{2\times 10}=0.5A\]


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