题目

When I became an amputee at age 29, I was forced to rethink the idea of physical perfection. My life became different, as I changed from an acceptably attractive woman to an object of pity and __1__. Too busy __2__ physical pain and obvious mobility limitation, I was not aware of this change at first. I was determined to _3__, feeling good about the progress I had made, as I moved forward. __4__, as I made my first excursion outside the hospital, society had already assigned me a new status. Happy to be free of my restriction in the hospital, I rolled through the shopping mall – a __5_17．固定在匀强磁场中的正方形导线框abcd各边长为L，其中ab是一段电阻为R的均匀电阻丝，其余三边均为电阻可忽略的铜线，磁感应强度为B，方向垂直纸面向里，现有一段与ab完全相同的电阻丝PQ架在导线框上，如图所示，以恒定的速度v从ad滑向bc，当PQ滑过$\frac{1}{3}$的距离时，通过aP段电阻丝的电流强度是多大？方向如何？