# A cylindrical cavity of diameter a exists inside a cylinder of diameter shown in the figure. Both the cylinder and the cavity are infinitely long. A uniform current density flows along the length. If the magnitude of the magnetic field at the point is given by , then the value of is ## Question ID - 153954 :- A cylindrical cavity of diameter a exists inside a cylinder of diameter shown in the figure. Both the cylinder and the cavity are infinitely long. A uniform current density flows along the length. If the magnitude of the magnetic field at the point is given by , then the value of is 3537

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A small coil with turns is mounted on one end of a balance beam and introduced between the poles of an electromagnet as shown in the figure. The area of the coil is , the length of the right arm of the balance beam is cm . When there is no current in the coil the balance is in equilibrium. On passing a current mAthrough the coil, equilibrium is restored by putting an additional weight of mass mg on the balance pan. Find the magnetic induction field (in terms of T) between the poles of the electromagnet, assuming it to be uniform  