When a metal slab is inserted between the plates of a parallel plate capacitor, it significantly alters the capacitance. This slab has a thickness , which is less than the separation distance between the plates. Even though the slab doesn’t touch the plates, it divides the space into two regions, essentially forming two capacitors in series.The metal slab increases the capacitance because it shortens the effective distance between oppositely charged regions, enhancing the electric field strength. This alteration can be visualized as two new capacitors, each having a separation of .
Calculating the modified capacitance involves understanding these regions:
- The effective separation between the two outside faces of the slab itself.
- The reduced effective distance .
The capacitance increases approximately as a factor of times , as derived from analyzing capacitors in series.