Why doesn't capacitance decrease with increase in temperature?

In summary, capacitance does not decrease with an increase in temperature because conductivity and capacitance are not directly related. While conductivity increases with temperature, this does not have a significant effect on capacitance. Additionally, the permittivity of the dielectric in a capacitor decreases with temperature, which leads to a decrease in capacitance. The random movement of molecules at higher temperatures also contributes to a decrease in capacitance.
  • #1
ARAVIND113122
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why doesn't capacitance decrease with increase in temperature??

It is known that conductivity increases with temperature.This is because heat provides kinetic energy to the electrons in a substance,thus increasing the rate of "flow" of electrons.Considering this,the electrons in a dielectric in a capacitor should also get excited on heating.This means the electrons are more likely to break away from one end and would travel to the other end.This means that the CAPACITY OF THE DIELECTRIC TO RESIST THE FLOW OF CHARGES[which in fact the capacitance of dielectric in the given set up] MUST DECREASE,WITH INCREASE IN TEMPERATURE.
am i right or is there something more to it??
please help me.
 
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  • #2


Energy in capacitor in stored in electric field between the plates of capacitor.By changing T you are not influencing C.Remember this
 
  • #3


the question is-why? what is wrong in the explanation i have given?
Wouldn't increasing temperature excite the electrons and thus,reduce the ability of the dielectric to prevent the charges from flowing?
if you look at what a capacitor really is-it is a device that helps in maintaining a potential difference without allowing the charges to flow.It is this ability that is called capacitance.A good capacitor can hold more more charges without breaking down.But if the charges are highly excited[i.e, the temperature is very high],then the capacitor cannot "hold" them.So,at different temperatures,the same set up will have different capacitance.Isn't it?
 
  • #4


ARAVIND113122 said:
It is known that conductivity increases with temperature.This is because heat provides kinetic energy to the electrons in a substance,thus increasing the rate of "flow" of electrons.Considering this,the electrons in a dielectric in a capacitor should also get excited on heating.This means the electrons are more likely to break away from one end and would travel to the other end.This means that the CAPACITY OF THE DIELECTRIC TO RESIST THE FLOW OF CHARGES[which in fact the capacitance of dielectric in the given set up] MUST DECREASE,WITH INCREASE IN TEMPERATURE.
am i right or is there something more to it??
please help me.

you have a few bad assumptions in your reasoning. from wiki...

Temperature dependence
In general, electrical resistivity of metals increases with temperature, while the resistivity of intrinsic semiconductors decreases with increasing temperature. In both cases, electron–phonon interactions can play a key role. At high temperatures, the resistance of a metal increases linearly with temperature. As the temperature of a metal is reduced, the temperature dependence of resistivity follows a power law function of temperature.

and to add to your misunderstanding... think of superconductors research and use...

They are not hot are they ? rather they are supercooled

cheers
Dave
 
  • #5
  • #6
If the conductivity is higher you don't get a higher capacitance, you get more leakage.
What you want it the permittivity. I looked up a capacitor data sheet, and there seems to be a maximum usually.

http://www.niccomp.com/Products/TC_Ceramics.pdf"

I think capacitance goes down for higher temperatures, because the random movement of the molecules will undo the polarization.
 
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1. Why does capacitance decrease with increase in temperature?

Capacitance is the ability of a capacitor to store electrical energy. It is affected by temperature because as temperature increases, the molecules in the capacitor vibrate more and create more resistance, which reduces the ability of the capacitor to store charge. This decrease in capacitance is due to the increase in dielectric loss and leakage current.

2. How does temperature affect the dielectric constant of a capacitor?

The dielectric constant is a measure of a material's ability to store electrical energy. As temperature increases, the molecules in the dielectric material move more and cause a decrease in the dielectric constant. This results in a decrease in capacitance since capacitance is directly proportional to the dielectric constant.

3. Does the type of dielectric material affect the decrease in capacitance with temperature?

Yes, different types of dielectric materials have different temperature coefficients, which determine how much the capacitance will decrease with temperature. Some materials, like ceramic, have a small temperature coefficient and therefore have a smaller decrease in capacitance compared to other materials like plastic which have a larger temperature coefficient.

4. Can temperature changes affect the accuracy of capacitors in electronic devices?

Yes, temperature changes can affect the accuracy of capacitors in electronic devices. This is because capacitance is an important factor in determining the performance of electronic circuits. As temperature changes, the capacitance also changes, which can lead to errors in the functioning of the circuit.

5. How can engineers compensate for the decrease in capacitance with temperature?

Engineers can compensate for the decrease in capacitance with temperature by using temperature-stable capacitors, which are specifically designed to have a small temperature coefficient and maintain a constant capacitance over a wide range of temperatures. They can also use temperature compensation techniques, such as using a combination of capacitors with different temperature coefficients to cancel out the overall temperature effect and maintain the desired capacitance.

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