A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10–12 F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?
Given: Capacitance of capacitor when medium between two plates is air, C = 8 pF = 8 × 10–12 F
Now, the capacitance of a parallel plate capacitor is given as:
where, A be the area of each plate
d be the distance between the two plates of the parallel plate capacitor
k is the dielectric constant, (for air , k = 1)
Capacitance, C = 8 pF(Given)
⇒
Suppose that the capacitance of the capacitor becomes C’ when the distance between the plates is reduced to half (d’ = d/2) and the space between them is filled with a substance of dielectric constant K = 6.
⇒
From equation (i) and (ii),
C’ = 12 x 8 x 10-12 = 96 x 10-12 = 96 pF