PPC with a dielectric slab in plates

If a dielectric slab of dielectric constant K, thickness t < d is placed between the plates of a PPC then due to the electric field between the capacitor plates the dielectric gets polarized & an electric is induced in it, as a consequence net electric field in dielectric is found to be .

Due to this field electric field net potential difference across the capacitor plates becomes .

Using C = q/V, capacitance of capacitor becomes .

1. If the entire space between the capacitor plates is occupied by air or vacuum, then .       [using K = 1 and t = 0]

2. If the entire space between the capacitor plates is occupied by dielectric, then            [using t = d]

Electric flux 

1. Electric flux (Φ_E) linked with a surface (flat or curved) gives us an idea of the total number of electric field lines passing normally through that surface.

2. Electric flux is defined as the surface integral of the electric field inked with that surface i.e.

Here θ is the angle between electric field vector & area vector ( i.e. an area vector conventionally directed normally outwards to the area under consideration).

3. SI unit of flux: Weber (Wb)

4. CGS unit of flux: Maxwell (Mx)

5. Conversion: 1Wb = 10 ⁸ Maxwell = 1Vm

6. Being dot product, electric flux is a scalar quantity.

7. Maximum value of flux = ± E S

8. Minimum value of flux = 0 (when θ = π/2)

9. If θ is acute flux is + ve & called leaving.

10. If θ is obtuse flux is – ve & called entering.