Question

Charge +q moving upward with speed V 18, A slight twist on the previous problem: Suppose that the magnetic field is uniform within an infinitely long cylindrical region of radius R, points into the paper, and has Cylindrical region of radius R poeby for magnitude given by: iudBo for t <o B(t)B Bo eat fort>0 where a is a positive constant with units t. At t-0, a point charge +Q of mass M is placed a distance r>R above (and outside of) the cylindrical region with an initial velocity V upward (away from the center). (a) What is the direction of the acceleration uniform in the of the charge immediately after t-0? (Circle one of the nine choices below.) (B into the paper and (B-0 outside of cylindrical region) cylindrical region) TO RIGI ZERO UPWARD DOWNWARD INTO PAGE CAN'T TELL, EITHER UP OR DOWN TO LEFT OUT OF PAGE CAN'T TELL, EITHER RIGHT OR LEF

Answer 1

Imagine a loop around the magnetic field, on which the charge lies. Magnetic flux through this loop is decreasing for . Thus, the induced electric field will be such that the motion of the charge resists the change in flux through this imaginary loop. The flux is decreasing in downwards direction, thus the induced electric field should be in clock wise direction, as that will imply an induced magnetic field in downwards direction, into the page, resisting the change in flux.

Imagine a loop around the magnetic field, on which the charge lies. Magnetic flux through this loop is decreasing for t > 0 . Thus, the induced electric field will be such that the motion of the charge resists the change in flux through this imaginary loop. The flux is decreasing in downwards direction, thus the induced electric field should be in clock wise direction, as that will imply an induced magnetic field in downwards direction, into the page, resisting the change in flux. Therefore, the acceleration of the charged particle will be TO RIGHT.

Therefore, the acceleration of the charged particle will be TO RIGHT.