Practical investigation on motors and generators

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Discussion Overview

The discussion revolves around a practical investigation into the behavior of a pendulum formed by a magnet and thread, specifically examining how its amplitude varies over time with or without the influence of a nearby electrical conductor. The scope includes theoretical development, experimental design, and measurement techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about how to begin the practical investigation and seeks ideas for developing a theory and selecting equipment.
  • Another participant suggests that the amplitude of the pendulum may decrease due to eddy currents generated in the conductor, leading to energy loss through heat, referencing a similar phenomenon observed when a magnet is dropped in a copper tube.
  • A participant thanks the previous contributor for the insights and expresses increased understanding of the topic.
  • Another participant inquires about methods for measuring the amplitude of the pendulum and confirms the use of a stopwatch for timing measurements.
  • A suggestion is made to create a protractor from cardboard to measure the angle of displacement, ensuring it does not interfere with the pendulum's motion, and to take measurements periodically during the swings.

Areas of Agreement / Disagreement

Participants generally agree on the approach to measuring amplitude and the potential effects of eddy currents, but there is no consensus on the specific theoretical framework or all aspects of the investigation.

Contextual Notes

Participants have not fully resolved the theoretical implications of their observations, and there may be additional factors influencing the pendulum's behavior that have not been discussed.

Who May Find This Useful

Students and educators interested in experimental physics, particularly those exploring concepts related to electromagnetism and pendulum motion.

applepie
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I'm not sure on what I have to do for this practical. I have to develop a theory and choose certain equipment for me to perform the investigation and obtain results... only i don't know where to start.

the aim is:
Investigate how the amplitude of a pendulum formed by a magnet and thread varies against time with or without a nearby electrical conductor.

Any ideas?!
 
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The changing magnetic field will generate eddy currents in the conductor, so I'm thinking the amplitude of the pendulum would decrease as energy is lost to heat through I^2 R.

A similar effect happens when you drop a strong magnet in a copper tube. It appears to defy gravity as it floats very slowly down the tube before falling out the other end. (Neat to watch...try it if you can find the materials)

Of course, there is probably more going on than that, but it's a start.
 
thanks PBRMEASAP! that was a great start :-p at least i think I am understanding abit more! thanks!
 
applepie said:
thanks PBRMEASAP! that was a great start :-p at least i think I am understanding abit more! thanks!

It sounds like a really cool experiment. Let us know what you find out!
 
does anyone know how to measure the amplitude??
time is with stopwatch right??
hope some one can help!
 
Make yourself a protractor out of cardboard and attach it to the pivot of the pendulum somehow (but don't let it interfere with the pendulum swing). Make it nice and big so that you can easily "eyeball" the angle the string makes with the vertical at maximum displacement. The pendulum should stay swinging for quite a while, so it should be sufficient to take a measurement every few swings, giving you time to write your measurement down. Yes, use a stopwatch to note the time at each measurement.
 

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