Question

To give an idea of sensitivity of the platypus's electric sense, how far from a 80nC n C point charge does the field have this magnitude

Answer 1

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

$\therefore E = \frac{kQ}{R^2}$

or $R^2=\frac{kQ}{E}$

    $R^2=\frac{9\times 10^9 \times 80 \times 10^{-9}}{0.002}$

   R = 600 m

This is the distance of the charge from the point of observations.