Question

To get an idea how big a farad is, suppose you want to make a 1-F air-filled parallel-plate capacitor for a circuit you are building. To make it a reasonable size, suppose you limit the plate area to What would the gap have to be between the plates? Is this practically achievable?

Answer 1

Answer:

• Gap between the plates $8.85\times 10^{- 16}\ m$
• No, practically not achievable

Solution:

As per the question:

Capacitance, C = 1 F

Area of the plate of the capacitor, A = $1\ cm^{2} = 1\times 10^{- 4}\ m^{2}$

Now,

To calculate the distance, D between the plates of a parallel plate capacitor:

$C = \frac{\epsilon_{o}A}{D}$

Thus

$D = \frac{\epsilon_{o}A}{C}$

where

$\epsilon_{o}$ = permittivity of free space

Now,

$D = \frac{8.85\times 10^{- 12}\times 1\times 10^{- 4}}{1}$

$D = 8.85\times 10^{- 16}\ m$

This distance much smaller and is practically not possible