Q 1.3: Check that the ratio is dimensionless. Look up a Table of Physical Constants and determine the value of this ratio. What does the ratio signify?
So the dimension of
The gravitational force between two bodies of mass M and m is
so dimension of
Therefor from (1) and (2)
K = , where is the permittivity of space.
e = Electric charge ([e] = [C])
G = Gravitational constant. ([G]= )
and are mass of electron and proton ( =  = [Kg])
Substituting these units, we get
Hence, this ratio is Dimensionless.
Putting the value of the constants
The given ratio is the ratio of electric force to the gravitational force between an electron and a proton considering the distance between them is constant!