Faraday's Law Demo: Eddy Pendulum

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This is a demonstration of the braking effect of eddy currents created through Faraday's law. A sheet of aluminum is attached to the bottom of a pendulum that swings freely through the poles of a horseshoe magnet. As the sheet passes through the poles, the changing magnetic flux in the aluminum generates an emf and currents, called eddy currents, in the aluminum. These currents induce magnetic fields that oppose the motion of the aluminum through the field, slowing its motion.

This demonstration was created at Utah State University by Professor Boyd F. Edwards, assisted by James Coburn (demonstration specialist), David Evans (videography), and Rebecca Whitney (closed captions), with support from Jan Sojka, Physics Department Head, and Robert Wagner, Executive Vice Provost and Dean of Academic and Instructional Services.

Physics Demos

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Exactly what I 😇😇😇 Thanq so much.... The content and explanation was in a nut shell and so was so much clear ... 😊

LaxBusiness

Sir your explanation is very good... Please upload on weekly basis.... You will hit millons... Soon.... Thank you thank you for great content

ArtByUmangKumar

Awesome explanation. No other video explains the direction of the currents and why they flow in that direction.

HJeff

Before automobile instruments became electronic, the speedometer worked on the same principle. A sheathed cable was attached to the drive train and was routed to the dash of the car. The cable turned a spinning magnet located behind an aluminum plate with a calibrated spring tension. The pointer for the speedometer was attached to the aluminum plate.

normkirkland

Thank you so much for making this demo (and your other demos) publc! This helps me understand the concepts related to Faraday's Law. Your articulation and demonstration is so helpful to the pursuit of understanding Physics, freely available on youtube, and a transcript too... Thank you! Hoping you get the Global Teacher Prize by the Varkey Foundation.

tmrfoushee

Nice to see that you are focusing on clearing the basic concepts of Physics via simple practicals which a lots of students can not get easily. Keep up the good work.

tirthapaul

Just wanted to say THANK YOU SO MUCH!! You helped so much with me Physics assignment, a clear and well explained video that was SO HELPFUL. :) :)

sophiemurphy

When he says EMF is produced, he means Electro-Motive Force, which is a fancy term for voltage. Remember voltage in Ohm's Law, V (or U in some parts of the world) = I * R. In this case the resistance is very small, less than 1 ohm. It would be nice to see this with a flat spiral coil of wire as the pendulum so that the current may be measured on a meter.

TechnoWzard

If wr oscillate the magnet, will the pendulum oscillate too?

awaansiddiqui

Since eddys are modifying the drag force in the differential equation (dimensionless for some constants {a, b}):
x''+F+a*sin(x)=0
I would like to know how you model the drag force under this extra drag:
1) like a Stokes' Law:
F=b*x' with a big parameter "b"?
2) like standard quadratic drag force
F=b*x'*|x'| with big "b"?
3) with a non-Lipschitz term of the form/similar

so it could have a finite extinction time?
4) another?

whatitmeans

Sometimes after seeing the demonstration, one doesn't need to explain to you more....you get it one's you watch it practically

rajshreenalawade

I've learnt something I never thought possible.

kentlandzintoba

For this experiment how powerful should the magnet be? Is it dependent on the mass of the pendulum?

thorbag

sir can we minimized these eddy current loss by using lamination using liquid in othet metal strip near by in contact the first sheet nd vibrating the two piece of metal strip in a strong magnetic field

arifullah