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

AI Thread Summary
Rotating the handle 90 degrees would alter the area exposed to the magnetic field, but it may not induce an EMF if the rotation is around a vertical axis, keeping the loop in the same plane. The other options, such as adjusting the resistance of the variable resistor or moving the handle towards and away from the coil, would affect the strength of the magnetic field and could potentially light the bulb. Clarification is needed on the axis of rotation for the handle and the direction of movement for the handle. The discussion highlights the importance of understanding how changes in area and magnetic field strength relate to induced EMF. Overall, the effectiveness of each action in lighting the bulb depends on the specific mechanics of the setup.
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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