Walter Lewin's Riddle at 37:00: The Surprising Conductor Plate Spark Explanation

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In summary, at 37:00 in the video, Walter Lewin demonstrates charging a conductor with a dielectric inside, removing the plates, and then putting them back in place. When he connects the plates, a spark is produced. The reason for this is that the dielectric remains polarized, causing the plates to become charged through induction. This can be further understood by considering the field and breakdown potential difference in a plane capacitor with a dielectric. Walter Lewin explains this phenomenon in more detail in his lecture.
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Nikitin
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At 37:00 he charges a conductor with a dielectric inside, removes the conductor plates and discharges them, and in the end puts them back into position.

Then something "remarkable" happens - when he connects the conductor plates with each-other, a spark is produced. Why did this happen?

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Is this because the dielectric is still polarized when he puts back the plates, and thus the plates themselves become charged (by induction) in turn? If not, what is the answer to this riddle?
 
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You're on the right track. If you want to put some math on it, consider the simpler case of a plane capacitor, with a dielectric and two gaps. Calculate the field both in the gaps and in the dielectric needed to have a potential difference around 20kV between the two plates, and compare to the breakdown field for air (around 3MV/m)
 
  • #4
How did he discover this?
 
  • #5
This is marvelous! I could listen to this guy the whole day :-)).
 

1. What is Walter Lewin's Riddle at 37:00 about?

Walter Lewin's Riddle at 37:00 is a physics phenomenon that occurs when a conductor plate is placed between two charged objects. It results in a spark being produced at the point where the conductor plate touches the charged objects.

2. Why is this riddle considered surprising?

This riddle is considered surprising because it goes against our common understanding of how electricity works. Typically, electricity follows the path of least resistance, but in this case, the spark is produced at the point of contact between the conductor plate and the charged objects, which may not seem like the path of least resistance.

3. What is the explanation for this surprising conductor plate spark?

The explanation lies in the concept of capacitance. When the conductor plate is placed between the two charged objects, it creates a capacitor. This capacitor stores electric charge, and when the charge builds up to a certain point, a spark is produced at the point of contact between the conductor plate and the charged objects.

4. How does this riddle relate to real-world applications?

This riddle has implications in various fields, including electronics, power transmission, and even lightning protection. Understanding capacitance and how it can produce sparks can help engineers design more efficient and safe electrical systems.

5. What can we learn from Walter Lewin's Riddle at 37:00?

This riddle teaches us that there is still much to be discovered and understood about electricity and its behavior. It also reminds us to question our assumptions and think outside the box when trying to solve scientific problems.

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