Physics question, someone please help me! Here is the question: As shown in the
ID: 1261818 • Letter: P
Question
Physics question, someone please help me! Here is the question:
As shown in the figure, two frictionless conducting rails (1 and 2) are attached to a 20.0 degree incline such that the inside edges are 80.0 cm apart. A copper bar with a mass of 0.202 kg slides (without friction) at a constant speed down the conducting rails. If there is a vertical magnetic field of 0.0516 T in magnitude in the region of the incline, determine the magnitude of the current I that flows through the sliding copper bar. What is the direction of the current in the sliding bar?Explanation / Answer
Note that the force experienced on a magnetic field by the wire is
F(B) = B I L cos (A),
where I = the current
L = the length of the bar = 0.80 m
The force of the weight down the incline if
F(W) = m g sin(A)
As these forces must cancel,
BIL cos A - mg sin A = 0
--> I = [mg tan A]/[BL]
Evaluating,
I = 17.45 A [ANSWER, PART A]
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As it is moving down, the flux due to the field decreases as the area decreases.
Thus, it will do something to keep the flux from changing.
It must produce a field that "supports" the field down the incline, which is only possible when the current is from RAIL 2 TO RAIL 1. [ANSWER, PART B]