1) The electrons in a dielectric are not free to move across the material becaus
ID: 1520209 • Letter: 1
Question
1) The electrons in a dielectric are not free to move across the material because they’re stuck to the nuclei of their host molecules. However, the distribution of electrons around a molecule can change. In other words, electrons can be pushed or pulled from one side of their host molecules to the other as long as they stay close to the nuclei. Keeping this in mind, explain why electrically neutral dielectrics, such as small bits of paper, are attracted to charged objects.
2) Now consider a fully charged air-gap capacitor that’s attached to a battery.
a) When you insert a dielectric between the plates, how do the electrons in the dielectric respond to the charges on the plates?
b) Then, how does the charge on the plates change in response to the new arrangement of electrons in the dielectric? What effect, if any, does this have on the capacitance of the capacitor?
3) What/which microscopic property/properties make a dielectric more effective?
Explanation / Answer
1)In this case, when a negatively charged object gets close to an uncharged object, electrons in the uncharged object are repelled, leaving the positive charges behind. These positive charges are then attracted to the negatively charged object. Thus tiny bits of paper which are uncharged are attracted towards a negatively charged object.
2)When a dielectric material is inserted between the plates, then due to polarization of charges on either side of the dielectric, it produces an electric field of its own which acts in a direction opposite to that of the field due to the source.
This makes the net electric flux zero. This effect results in increase in capacitance.
3)Dielectric constant-higher the dielectric constant , more effective
dielectric loss- lower the dielectric loss , more effective is the dielectric material
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