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Consider a system, of a rail-like input connector transferring input current goi

ID: 3349532 • Letter: C

Question

Consider a system, of a rail-like input connector transferring input current going (downward) and delivering power to a slider, the slider also delivers current-while moving to other components, the current is always in the downward(-y) direction.

The following diagrams (1-3) are composed of different frames of time, one at the initial stage where there is no motion(diagram1), another in the stage of change in position (digram2 - midway), and finally the last frame that has no motion and the slider has reached the final input connector(diagram3).

NOTE: The slider, is moving from an exterior force.

From the start, till the end:

1) Is there a Lorentz force in the 3-frames? Explain.

2) In what direction is the Lorentz force, and why?

3) Is there an induced EMF? On what components (slider, or input connector(gray)) and what direction?

Please explain.

Diagram 1:

Diagram 2:

Diagram 3:

intial position

Explanation / Answer

We know that

Lorentz Force=qE+q(vxB)

q is charge , v is velocity , B is magnetic field .

1)

Since there is no velocity in frame 3

Hence , Lorentz force becomes 0

Hence , no Lorentz force

2)

The direction of magnetic field is given by . As we know that magnetic field direction is given by curling the fingers arround the current carrying conductor .

Now , using Lorentz force rule .

Direction of vxB gives direction of Lorentz force

Direcion of force is given as along that of direction of conductor using vector cross multiplication rule .

3)

emf = (Change in flux)/(Change in time)

=B.A/t

=BvL

L is length of conductor

v is velocity

B is magnetic field