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?

Solution:

As per the question:

Capacitance, C = 1 F

Area of the plate of the capacitor, A =

Now,

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

Thus

where

= permittivity of free space

Now,

This distance much smaller and is practically not possible

f=gm1m2/d^2 it d

f is force g is gravitaiton constant, m1 is mass of first object, m2 is mass of second object. d is distance between two object

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible