The 3.0-V flashlight bulb and wire loop assembly of Problem 62 is now attached to a wooden dowel with a crank handle as shown in Figure P21.63, and the loop is rotated in a uniform magnetic field of 2.5 T.
(a) The crank arm rotates, and for simplicity assume the flux changes from zero to its maximum value in 1/4 period of rotation. What value of the period is just small enough to light the bulb?
(b) If the magnitude of the field is reduced to 0.25 T, what is the smallest value of the period that will work?

 

Figure P21.63