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Homework Statement
Below are a few equations listed in my text for use in calculating capacitance in dielectrics. I'm wondering which of these are applicable in specific scenarios
Homework Equations
1. k = C/C0 - with C0 indicating capacitance w/o dielectric
2. v = v0/k
3. E = E0/k
4. σi = σ(1 - 1/k) - subscript i indicating induced charge density on dielectric
5. ε = kε0 - ε is permittivity of dielectric
6. E = σ/ε - E is the E field in the dielectric, σ is the surface charge density of the capacitor plate.
7. C = kC0 = εA/d
8. u = 1/2kε0E^2 = 1/2εE^2 - u being the energy density of the dielectric
The Attempt at a Solution
From what I understand, all these equations can be used in a case where a dielectric is inserted into a charged capacitor that was already disconnected from the power source. My question is regarding the use of these equations when the dielectric is inserted while the capacitor is still connected to the power source as Q is increased and V is held constant in this case.
Here are my assumptions:
1. Holds because it is a general equation
2. Doesn't hold because it was derived with the assumption that Q is constant and V is not
3. Doesn't hold because it was derived with the assumption that Q is constant.
4. Doesn't hold because it was derived using the assumption that E between the capacitor decreases rather than increases.
5. Holds because k can be derived from 1
6. Holds because ε is from 5
7. Holds because k can be derived from 1
8. Holds because ε is from 5
May I know if my assumptions are wrong? Any help is greatly appreciated.