A 490 pF capacitor consists of two 19 cm -radius circular plates, insulated with polystyrene
Find the thickness of the polystyrene.
2. Relevant equations
d = (ε_0 * Area * K) / C
3. The attempt at a solution
I converted 490 pF to F
4.90 * 10^-10 F
I converted 19 cm to meters
and found the area of the plate
∏r^2 = ∏(.19)^2 = .1134 m^2
K of polystyrene = 2.3, so now just plug everything into my equation
d = ((2.3) * (8.854*10^-12) * (.1134)) / (4.9 * 10^-10)
d = .00471 m
I want my answer in mm with two significant figures
d = 4.7 mm
mastering physics tells me this is the wrong answer, where did I go wrong?