Does an electrically charged surface maintain an excess charge if heated?

In summary, the conversation discusses the relationship between electric charge and thermal radiation, specifically in the context of two conductors connected to a battery. It is suggested that at high temperatures, the extra thermal energy may begin to pump off electrons from the surface, creating an electron cloud. However, it is also noted that there must be some material breakdown with air or impurities present. The conversation concludes with the idea that thermal energy at a certain level could potentially create a net charge on a surface, similar to an applied voltage potential.
  • #1
uby
176
0
Suppose I were to take two conductors and connect one of each to the negative and positive terminals of a battery. After some time, the conductors should be at equilibrium with the voltage potentials of the battery (i.e. - one conductor should be at +V and the other at -V having developed by the net loss and gain of electrons, respectively). Removing the battery essentially forms a capacitor: each plate being charged and, when connected electrically, will discharge. However, if these plates are never connected electrically, they should in theory maintain their potentials forever.

Now, what if one were to heat these plates to a very high temperature (one at which significant blackbody radiation would occur, say above 2000C). Would these plates maintain their charge potentials?

Would it matter what atmosphere they were in? (i.e. - a perfect vacuum is perfectly insulating, vs. air which can be regarded as a dielectric)

Would it matter how they were heated? (i.e. - via radiative heat transfer vs. Joule heated via inductive coupling)

I'm just trying to figure out if a surface can maintain a charge applied at room temperature at high temperatures, and under what conditions the charge can be dissipated.

Thanks!
 
Physics news on Phys.org
  • #2
Electric charge consists of electrons and holes while thermal radiation consists of waves of energy or photons...so even though a hot body radiates it should still be charged...but at some temperature the extra thermal energy must begin to pump off, boil off the most excited electrons, ...I'm not sure about "holes"...

that's how a vacuum tube works: a current and negative charge is applied to a hot cathode and a positive anode at the other end of the vacuum tube attracts the electrons emitted from the hot cathode.

There MUST be some material breakdown with air or other impurities present...otherwise vacuum tubes and bulbs would not be evacuated...

I'm just trying to figure out if a surface can maintain a charge applied at room temperature at high temperatures, and under what conditions the charge can be dissipated.

Try reading this on vacuum tubes...lots of background explanation:
http://en.wikipedia.org/wiki/Vacuum_tube
 
  • #3
thanks for your reply naty! this gives me a new avenue of directions to look into.

from my cursory review of the keywords you suggested, it appears that, even in the absence of a complete electrical circuit, electrons can boil off the surface if their thermal energy exceeds the binding energy due to electric potential and create an electron cloud near the surface - though of course, on the whole, no net change in charge will occur in the system.

my back of the envelope calculations regarding my intended application are interesting nonetheless. I'm sure there is a huge amount of literature on the subject to peruse. thanks again!
 
  • #4
electrons can boil off the surface if their thermal energy exceeds the binding energy due to electric potential and create an electron cloud near the surface - though of course, on the whole, no net change in charge will occur in the system.

yes to the first part; but for the second part I'd guess thermal energy at some level COULD create a net charge... just as an applied voltage potential can.
 
  • #5


I can provide some insights into this question. First of all, it is important to understand that temperature and charge are two separate physical properties. Heating a surface does not directly affect its electrical charge. However, there are some factors that can indirectly affect the charge on a surface when it is heated.

Firstly, the atmosphere in which the charged surface is located can play a role. In a vacuum, there is no medium through which electrons can flow, so the charge on the surface will remain stable. However, in an atmosphere with gases present, the charged surface may experience a phenomenon known as corona discharge. This is when the electric field around the surface becomes strong enough to ionize the surrounding gas molecules, leading to a flow of charge. So, in this case, the charged surface may lose its excess charge over time due to the presence of an atmosphere.

Secondly, the method of heating can also affect the charge on a surface. If the surface is heated through radiative heat transfer, the electromagnetic radiation can potentially ionize the surrounding gas molecules and cause a flow of charge. On the other hand, if the surface is heated through inductive coupling, the electric field around the surface may be affected, potentially leading to a redistribution of charge.

In summary, while heating a surface does not directly affect its electrical charge, there are factors such as the surrounding atmosphere and heating method that can indirectly impact the charge on the surface. It is also worth noting that the charge on a surface can dissipate over time due to various factors, such as leakage or corona discharge. So, while the surface may maintain its charge potential at high temperatures, it may not necessarily do so indefinitely. Further research and experimentation would be needed to fully understand the behavior of charged surfaces at elevated temperatures.
 

1. What is the relation between heat and electrical charge on a surface?

When a surface is heated, the atoms and molecules within it gain energy and begin to vibrate more vigorously. This increased movement can cause electrons to move away from their original positions, resulting in an overall decrease in the surface's electrical charge.

2. Does the type of material affect how an electrically charged surface responds to heat?

Yes, different materials have varying abilities to conduct heat and retain electrical charge. For example, metals are better conductors of both heat and electricity, so they may lose their electrical charge more quickly when heated compared to non-metal materials.

3. Can an electrically charged surface maintain its charge if heated to extremely high temperatures?

No, there is a limit to how much heat a surface can withstand before its electrical charge is completely dissipated. At extremely high temperatures, the atoms and molecules in the surface may become ionized and lose their electrons, resulting in a neutral charge.

4. How does the environment (e.g. air, water) affect the retention of electrical charge on a heated surface?

The presence of air or water can affect the retention of electrical charge on a heated surface by providing a medium for the charge to dissipate. For example, if a surface is heated in a humid environment, the water molecules in the air may absorb some of the excess charge and reduce the overall charge on the surface.

5. Does the shape or size of a surface impact how it maintains an electrical charge when heated?

Yes, the shape and size of a surface can affect how it maintains an electrical charge when heated. For instance, a larger surface may have a larger area for the charge to distribute, making it less likely to maintain a high electrical charge compared to a smaller surface with less area for the charge to dissipate.

Similar threads

  • Electromagnetism
Replies
16
Views
402
Replies
11
Views
698
  • Electromagnetism
2
Replies
36
Views
2K
Replies
4
Views
894
  • Electromagnetism
Replies
15
Views
861
  • Electromagnetism
Replies
8
Views
877
Replies
3
Views
346
Replies
7
Views
942
  • Electromagnetism
Replies
4
Views
812
Replies
8
Views
1K
Back
Top