I have a problem about Barlow's wheel experiment with several questions. One of them is how to increase the angular velocity for the wheel.
I can either:
1. Increase the current
2. Increase the radius
3. Increase the strength of the magnetic field
4. Decrease friction
Are there any other ways to increase the speed?
Also, Wikipedia says that using an electro-magnet instead of a permanent magnet will cause more rapid revolution, I don't see why, can someone explain this?
"The points of the wheel, R, dip into mercury contained in a groove hollowed in the stand. A more rapid revolution will be obtained if a small electro-magnet be substituted for a steel magnet, as is shown in the cut. The electro-magnet is fixed to the stand, and included in the circuit with the spur-wheel, so that the current flows through them in succession. Hence the direction of the rotation will not be changed by reversing that of the current; since the polarity of the electromagnet will also be reversed."
2. Homework Equations