This Studio project combined mechanics with electromagnetism. The e.m.f. induced in a set of vertically displaced coils as a magnet was thrown inside a cylindrical column was measured. The data was imported into a computer and speeds of the falling magnets were determined using two approaches. One was a naive approach determining speed from distance divide by transit time. The distance was the length of the coil. In a more accurate approach, however, we theoretically investigated the magnetic field due to a moving dipole inside a pickup coil. From this a mathematical model was derived which was fit onto experimentally determined curves, yielding accurate estimates of the velocities.
An interesting demonstration of eddy current Plastic pipeis made by dropping a spherical or a cylindrical magnet down a copper pipe. The magnet does not fall as quickly as it falls due to gravity alone, showing the eddy currents induced in the copper pipe oppose the change in magnetic filed by creating opposing magnetic fields which slows the fall of the magnet.
The experimental objective is to use a Hall sensor and to find the field and magnetization of a magnet. We will also gain practical knowledge of magnetic field transducers, hard disk operation and data storage, visually and analytically determining the relationship between induced EMF and magnetic flux, and indirectly measure the speed of a motor.
|Sample Results||Hall probeSolenoidDistance vs magnetic field strengthGeometric function vs magnetic strength|
|Version||31st August 2015, 2015-v1|
Further Readings and References
- An Experimental Observation of Faraday’s Law of Induction American Journal of Physics , R. Kingman, S. C. Rowland, and S. Popescu , 70(6) 595 , (2002).
- Faraday’s Law – Quantitative Experiments American Journal of Physics , R. C. Nicklin , 54(2) 422 , (1986).
- The Hard Drive: An Experiment for Faraday’s Law The Physics Teacher , B. Hinaus, M. Veum , 40 339 , (2002).
- Apparatus for teaching Physics – Measurement and Analysis of the Field of Disk Magnets The Physics Teacher , M. Connors , 40 308 , (2002).