The question is incomplete. The complete question is :
A platypus foraging for prey can detect an electric field as small as 0.002 N/C.
-To give an idea of sensitivity of the platypus's electric sense, how far from a +80nC point charge does the field have this magnitude?
Solution :
Given electric field, E = 0.002 N/C
Charge, Q = + 80 nC
[tex]$\therefore E = \frac{kQ}{R^2} $[/tex]
or [tex]$R^2=\frac{kQ}{E}$[/tex]
[tex]$R^2=\frac{9\times 10^9 \times 80 \times 10^{-9}}{0.002}$[/tex]
R = 600 m
This is the distance of the charge from the point of observations.
