Massachusetts Institute of Technology
Sign in

Dissectible Capacitor

Leyden Jars, an early style of capacitor, can be connected to the two electrodes of the Wimshurst Machine. They will store charge as it is generated, giving a much stronger spark across the gap.

Next we have a three-piece dissectible Leyden Jar consisting of two metal cups separated by a glass cup. When charged with the Wimshurst machine, we see by touching it with the shorting rod that it holds a large amount of charge. However, when disassembled, the metal cups can be brought into contact with each other and no spark will be generated. When the jar is reassembled it can then be discharged. This demonstrates that, in this situation, the charge actually resides on the surface of the glass (a dielectric), not on the metal.

Comments (1)

Question: is it important that the glass is in contact with the metal, ie, is there an actual charge transfer, or is the capacitor field inducing a charge separation (polarization) inside the glass? If it is the latter (and physics texts typically offer this as the explanation for the dielectric effect), then it is subtle that the Leyden jars allow a large amount of charge to be collected. If the phenomenon is that the charge flows (separates) via the contact with the metal, then the explanation is more obvious, but not along the lines of what is offered in textbooks.

Posted over 7 years by Anonymous

You need to log in, in order to post comments.

MIT Department of Physics Technical Services Group

MIT Department of Physics Technical Services Group

Category: Science | Updated over 6 years ago

Created
January 22, 2009 15:13
Category
Tags
License
Creative Commons Attribution-NonCommercial (What is this?)
Additional Files


Viewed
50299 times

More from MIT Department of Physics Technical Services Group

Moving Sand Cart Over a Rotating Surface

Moving Sand Cart Over a Rotating Su...

Added over 7 years ago | 00:01:13 | 37384 views

Monkey and a Gun

Monkey and a Gun

Added over 8 years ago | 00:01:16 | 72565 views

MIT Physics Demo -- Levitating Magnet

MIT Physics Demo -- Levitating Magnet

Added over 8 years ago | 00:00:47 | 44526 views

Push Me, Pull You

Push Me, Pull You

Added 8 years ago | 00:01:42 | 37375 views

MIT Physics Demo -- Conductivity of Ionized Water

MIT Physics Demo -- Conductivity of...

Added over 8 years ago | 00:00:53 | 50483 views

Fire Extinguisher on a Tricycle

Fire Extinguisher on a Tricycle

Added 8 years ago | 00:00:53 | 40641 views