Can a capacitor increase voltage beyond initial charge?

Click For Summary

Discussion Overview

The discussion centers around the behavior of a capacitor when charged and then separated, specifically whether the voltage can exceed the initial voltage of the power source after separation. It explores theoretical implications and the underlying physics of capacitance and voltage relationships.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions if separating the plates of a charged capacitor can lead to voltage spikes beyond the initial charge, suggesting it seems counterintuitive.
  • Another participant explains that as the plates are pulled apart, the capacitance decreases, which, with constant charge, implies an increase in voltage according to the equation Q = CV.
  • A participant expresses realization about the work done in separating the plates and seeks clarification on whether the voltage can exceed the initial source voltage.
  • One participant asserts that the voltage can indeed be higher than the initial source, provided the voltage source is disconnected before separating the plates.

Areas of Agreement / Disagreement

Participants express varying levels of understanding about the implications of separating capacitor plates, with some agreeing that voltage can increase beyond the initial source under certain conditions, while others seek further clarification on the mechanics involved.

Contextual Notes

There are assumptions regarding the conditions under which the voltage may increase, such as the necessity of disconnecting the voltage source before separation. The discussion does not resolve the implications of these assumptions fully.

Blackhawk4560
Messages
19
Reaction score
0
Question: If you charge a capacitor circuit and then separate the capacitor, does voltage increase beyond the initial source?

It seams counter intuitive that if you plug a 9 Volt battery into two metal plates and pull the plates apart that you'll get massive voltage spikes, but that's what the equations seem to point to...

You'll see a diagram of this attached,
Thanks for your time!
 

Attachments

  • Voltage Change.png
    Voltage Change.png
    19.4 KB · Views: 598
Physics news on Phys.org
Blackhawk4560 said:
t seams counter intuitive that if you plug a 9 Volt battery into two metal plates and pull the plates apart
Why counter-intuitive ? You yourself already write you need to pull (i.e. do work) the plates apart.

The capacitance decreases, so, in accordance with Q = CV the voltage must increase if the charge remains the same.

By the way, the guy's name is 'van de Graaff'
 
Ohhhhhhhh I hadn't thought of that work being done... makes sense!

Can that lead to the voltage being HIGHER than the initial source? Or does it cap off at the voltage of the battery/van de GraAff?

Thanks again, blown away by that response time by the way!
 
Blackhawk4560 said:
Can that lead to the voltage being HIGHER than the initial source
Yes. Of course, you first have to disconnect the voltage source before starting to pull on the plates.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 22 ·
Replies
22
Views
5K
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 4 ·
Replies
4
Views
6K
  • · Replies 20 ·
Replies
20
Views
11K