## College Physics (4th Edition)

The rat must come within $1.3~meters$ of the charge.
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.