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Q & A: Casimir effect on capacitors

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Most recent answer: 06/26/2008
Q:
while considering ultra capacitors recently, it occured to me that the Casimir force appears between conductive plates very close together, separated by vacume. i looked up the distances involved and according to wikipedia, at about 10nm separation, there is a pressure equal to 1 atmosphere. according to www.worldandi.com, recent ultra capacitors have been made with a separation of the order of nano meters. are fluctuations in the quantum field affecting the storage capacity of modern ultra capacitors?
- peter carlyle (age 32)
brisbane, queensland, australia
A:
That's a really interesting question. I think there's no real problem, because the sorts of materials in those capacitors can easily withstand much larger forces. 
I bet the Casimir calculation is done assuming there's a vacuum between the plates. It's not hard to calculate the attractive force due to, say, a 3V potential on the capacitor with 10 nm plate separation. It would be somewhat larger than the force from the Casimir effect. Inclusion of a dielectric material would increase the ordinary electrical force on the plates, for a given voltage. I'm not sure how it would affect the Casimir force.

In general you're right, however, that special finite-size quantum effects are becoming important in nanoelectronics. Also simple statistical fluctuations in the number of charge carriers become important in small transistors, etc.

Mike W.

(published on 06/26/2008)

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