The figure below shows two parallel conducting rails, oriented vertically, conne
ID: 33599 • Letter: T
Question
The figure below shows two parallel conducting rails, oriented vertically, connected to each other at the top by a wire with a resistance R. A conducting metal rod is oriented horizontally and is in contact with the two vertical rails. The horizontal rod has a length
L = 55.7 cm and mass 24.3 g. The rod is released from rest at location A and begins to fall through a region of uniform magnetic field indicated by the shaded area in the figure. When the rod reaches point B, there is an induced current of 2.15 A flowing to the right in the rod, and the rod is moving downward with an acceleration of magnitude 7.85 m/s2.
What are the direction and magnitude of the magnetic field in the shaded region?
Magnitude: ________T
Direction: (upward, downward, toward to the left, toward to the right, into the page, out of the page)
Explanation / Answer
Force on the rod due to magnetic field = iLB (B is perpendicular to the plane)
F = 2.15 * 0.557 * B
Now writing Dynamic equation for the rod
Forces acting on rods are its weight ,W downward Magnetic force,F upwards
W-F = Ma
24.3*9.8/1000 - 24.3/1000 * 7.85 = 2.15 * 0.557 * B
B= 0.039 T (ans)
And direction of magnetic field is into the plane (ans)