Answer
The rat must come within $1.3~meters$ of the charge.
Work Step by Step
We can find the distance $r$ from the charge where the electric field is $5.0~kN/C$:
$E = \frac{k~q}{r^2}$
$r^2 = \frac{k~q}{E}$
$r = \sqrt{\frac{k~q}{E}}$
$r = \sqrt{\frac{(9.0\times 10^9~N~m^2/C^2)(1.0\times 10^{-6}~C)}{5.0\times 10^3~N/C}}$
$r = 1.3~m$
The rat must come within $1.3~meters$ of the charge.
