Why wouldn't rotating the handle 90 degrees induce an EMF?

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Homework Help Overview

The discussion revolves around an electromotive force (EMF) problem related to the effects of rotating an insulating handle in the context of a current-carrying coil. Participants explore how different actions might influence the ability to light a bulb.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants examine the implications of rotating the handle and how it affects the area exposed to the magnetic field. Questions are raised about the axis of rotation and the specific directions of movement for the handle.

Discussion Status

The discussion is ongoing, with some participants providing insights into the axis of rotation and its relevance to the problem. There is acknowledgment of the need for clarity regarding the specific actions described in the problem.

Contextual Notes

There is a lack of clarity regarding the orientation of the handle's rotation and the specific movements being considered, which may affect the interpretation of the problem.

bajerrrr
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Homework Statement


upload_2018-8-24_11-9-21.png

There is some current in the bottom coil.
The question asks which would not be able to light the lightbulb
- rotating the insulating handle 90 degrees
- increasing resistance of variable resistor
-reducing resistance of variable resistor
- moving the insulating handle towards and away from the current carrying coil.

Homework Equations


emf = change in magnetic flux over time.
right hand rule for current carrying wire
B = (permeability of free space * current)/ (2pi * radius)
magnetic flux = BA

The Attempt at a Solution


Rotating the handle 90 degrees would change the area exposed to the magnetic field. All the other choices would change the strength of the magnetic field. Wouldn't all of these choices be able to light the lightbulb?
 

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bajerrrr said:
Rotating the handle 90 degrees would change the area exposed to the magnetic field.
Perhaps they meant rotating the handle about a "vertical" axis, keeping the loop in the same plane.
 
Not clear:
1. Rotating the insulating handle which way? Around which axis? If you rotate the handle by 90 degrees about a vertical axi through the center of the coils, then nothing happens.
2. Moving the insulating handle towards and away from... Again, which way?
 
Thank you for the help, I did not consider the vertical axis.
 

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