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### Course: Class 12 Physics (India)>Unit 6

Lesson 6: Eddy currents

# Eddy currents & their applications (& how to reduce them)

Eddy currents are current loops formed over conductor surfaces due to changing magnetic flux. They are useful in induction heating, levitating, electromagnetic damping, and electromagnetic braking. They can be minimized by adding slots in the conductor surface & laminating. Created by Mahesh Shenoy.

## Want to join the conversation?

• sir in the last demonstration of lavitating coil i think you have depicted the wrong direction of current in it
• yes but that was not the focus of the video
(1 vote)
• Is Lenz's law applicable to all materials, regardless of whether they are diamagnetic, paramagnetic, or ferromagnetic?

Suppose a diamagnetic substance is introduced in a decreasing magnetic flux, would it be attracted or repelled?
• Hello! I went through this video and had a small doubt in the induction plate part.

If there is a current being induced in the vessel, which in turn heats it up.... Why don't I get electrocuted when I try to pick up the vessel while the induction plate is on?

The vessel is a conductor right? Doesn't that mean that I'm giving the currents an easier way to reach the ground the same way I do when I touch an open wire or something?

I tried looking it up on quora and I got the following answer but I couldn't really understand it (my bad):-

"Eddy currents in utensils heat the vessel, and make cooking possible. Eddy currents are limited to vessel base and there is not much voltage involved. Further, our body does not come into picture when induced current is concerned. Whole system is insulated including the top surface."

(1 vote)
• Not an expert but i would think that frequency of the current induced is either very high, higher than the frequency that cause humans pain or very low(you can checkout the frequency to pain chart on google), moreover the emf cant be induced over larger distances and its a similar reason why wireless phone chargers only work at very close distances(1-3 mm in my experience)
• In the last experiment(the spinning aluminum plate stopped by magnet), the total flux through the plate never changed right? How did it induce current then
(1 vote)
• For the pendulum experiment, what if the plate used were a circle and not a rectangle?
(1 vote)
• Then there would be variable emf induced (depending on dx) whereas for the rectangle for a given time, it was the same throughout the breadth.
(1 vote)
• When air acts an insulator, the resistance increases tremendously, due to which the current decreases. Shouldn't the heat loss also be increased as the resistance is increased?
(1 vote)
• Iam not an expert, but I think if the resistance increases, current decreases. and when current decreases power loss also decreases. The voltage is constant right, so due to I= V/R, since resistance tremondously increases, current descreases at a far greater value and since P=I squared R, power loss descreases. Lets day voltage is 20, current is 10 and resistance is 2. If resistance increases twice, that is 4 ohms, current descreases by 1/2, that is 5 amps (since V=IR). If P was equal to just IR then there will be no change, but actually P is equal to I 'squared' times R. So previosly when resistance was 2, power loss would be (10)squared x 2 = 200 joules. Now, power loss would be (5)squared x 4 = 100 joules. See, power loss has actually descreased, because even though resistance doubles (2 to 4 ohms), current goues down by 4, that is *10 squared) 100 to (5 squared) 25 Considering the equation p=isquared times r. I dont know if its correct, but i hope this helps you to get a start in thinking
(1 vote)