How a change of the magnetic moment μ of the magnet influences the induced emf? What does it mean to change the magnetic moment μ? How the induced emf is affected by reversing a magnet? How could you simulate this? Compare the experimental recorded data with the model results. Which model A or B come closer to your experimental data. Predict the induced emf graph when a second coil is placed in a series, at the distance d below the first coil? Can you predict the induced emf graph when a more than two coils (3, 4 or 5) are placed in series below each other at the equal distances between each other?
Analysing student activities Students work with a given model, they analyse it and use it to simulate different situations. In the model is assumed that the south pole of the magnet enters the coil first. The vertical position y and velocity v of a falling magnet can be found by motion equations: dy dv v and g where g is gravity acceleration. dt dt
The initial position of the magnet is h and its initial velocity is 0. There are two models available; the difference between them is the way of describing the magnetic flux change
d . dy
Model A: This model is based on the approximation of a point magnetic dipole,
d is dy
described by the equation 2.
Figure 22. Model A
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MOSEM2 Teacher Guide