PHYSICS 7D Lecture Notes - Lecture 10: Relative Permittivity, Dielectric, Electric Field
PHYSICS 7D verified notes
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Document Summary
So far, we have assumed that there is no material in the space between the plates of a capacitor. Now, fill the region between the plates with insulating material known as dielectrics. If you stick these materials into the capacitor, the capacitance goes up by a factor k: c=kc 0 , k is a dielectric constant. In the absence of an electric field, nonpolar molecules are not electric dipoles. Q=cv, with the same free charge q on plates, adding dielectric reduces the potential difference. Molecules in dielectrics can be as dipoles (+ - charge pairs) Non-polar dielectrics : symmetric shape (like benzene), get dipole moment when put into e, called induced dipole moment. In the absence of an electric field, polar molecules orient randomly. An electric field causes the molecules" positive and negative charges to separate slightly, making the molecule effectively polar. Molecular dipoles tend to align in e field.
