Electromagnets and Conductors: The Effects on a Pendulum

[XigmaTek]

Question:
Describe what will happen when a magnet suspended in the form of a pendulum is affected by an electrical conductor in close proximity.

My working:
Lenz's Law states that the emf induced in a conductor will oppose the emf of the change that produced it. Let's say I designed my experiment this way...

[PLAIN]http://img191.imageshack.us/img191/562/assessment.png
the dotted line represents the trajectory of the pendulum (should be a perfect parabola shape..)

The magnet moving over the sheet of metal will produce eddy currents in the metal, which will oppose the magnetic field caused by the magnet. Thus, this will cause the pendulum to slow down faster and its period and amplitude will decrease much quicker than if there was no conductor.

Am I correct? What else can be said about this situation? Is there a changing magnetic field present here?
Thank youuuuu!

 

[phyzguy]

What you said about the EM is basically correct, but a couple of comments:

(1) Pendulums move on a circular path, not a parabola.

(2) The period of a pendulum is pretty much independent of the amplitude. The amplitude will decrease, but the period will not change.

 

[XigmaTek]

thanks for that info. but your second point would apply only to small angles.
how would i go about measuring the amplitude?
also, does it matter which end of the magnet (N or S) is facing the sheet of metal as it moves over it?

 

[phyzguy]

thanks for that info. but your second point would apply only to small angles.
how would i go about measuring the amplitude?
also, does it matter which end of the magnet (N or S) is facing the sheet of metal as it moves over it?

-You are correct, the period is only independent of amplitude only for small angles.
-To measure the amplitude, you need to measure the maximum deflection. You could take a time exposure picture or a movie and measure it off the picture.
-It doesn't matter whether it is the N or S pole, the effect is the same.