The strength of a bar magnet's magnetic field decreases with distance according to what is known as an inverse cube law; multipl
ying the distance from the magnet by a factor of k divides the magnetic field strength by a factor of k^3. Suppose the magnetic field strength of the magnet is 64 Gauss at a distance of 10 cm away. What is the magnetic field strength of the magnet, 20 cm away?
