Final answer:
The electric field outside the capacitor plates diminishes swiftly due to fringe effects. The strength of the field between the plates is proportional to the surface charge density, whereas the insertion of a dielectric induces an additional electric field, affecting the net field within the capacitor.
Step-by-step explanation:
The field outside the capacitor plates, often referred to in physics as the electric field or E-field, is an area of influence generated by the electric charges on the plates of the capacitor. Within the context of a parallel-plate capacitor, the electric field lines begin on the positive charge on one plate and end on the negative charge of the other plate, implying that outside the plates, the electric field diminishes rapidly due to fringe effects.
Applying a dielectric to the capacitor affects the overall field, with an induced electric field Ei appearing due to the induced charge Qi on the surfaces of the dielectric material.
The magnitude of the electric field E within the region between the plates is given by E = σ/ε₀, where σ denotes the surface charge density on one plate, while ε₀ is the vacuum permittivity. This field strength is directly proportional to the surface charge density σ, which is the charge Q per surface area A of the plates.
Yet, when the dielectric is introduced, the net electric field E is the vector sum of the original electric field due to the free charge Q₀ and the induced electric field Ei due to the induced charge Qi.