2. The plates of a parallel-plate capacity carry surface charge density σ C/m². A dielectric slab of thickness t and dielectric Constant κ is inserted into the parallel plate capacitor with plates of area A, separated by distance d, as shown in Fig.1. Assume that the battery is disconnected before the slab is inserted.
What is the total potential difference between the plates? (2) ___ V.
What is the capacitance C₁ between the plates? (3) ___ nF.
If the dielectric slab is replaced by a metal sheet with the thickness t, compared to the capacitance C₁, how is the capacitance affected? (increase? decrease? or keep constant?) (4) ___
(Take d = 1 cm, t = 0.3 cm, σ = 2 nC/m², κ = 5, A = 40 cm², ε₀=8.85×10⁻¹² F/m.)