Check that the ratio `ke^(2)//Gm_(e) m_(p)` is dimensionless, Look up a table of Physical Constants and determine the value of this ratio. What does the ratio signify ?

Explanation

(a) Refer to Art.
(b) As electric charge is quantised, `q = +- n e` where `e = 1.6xx10^(-19) C`
At macrocopic level, one deals with charges that are enormous compared to the magnitude of charge (e), For example, when `q = 1 muC = 10^(-6) C`
`n = (q)/(e) = (10^(-6))/(1.6xx10^(-19)) = 6.2xx10^(1//2)`
i.e., a charge of `1 mu C` contains `6.2xx10^(12)` electrons. The fact that charge can increase or decrease only in units fo 'e' when `10^(12)` electrons charges are involved has almost no significance. Thus at the macroscopic level, graniness of electric charge or quantisation of electric chare is of no practical consequence. It can be ignored and electric charge can be considered as continous.