A cylindrical bar magnet of radius 1.0 cm and length 10 cm has a magnetic dipole moment of magnitude m = 2.0 A · m².What is the magnetic field just outside one end of the magnet? A)40 mT B)80 mT C)32 mT D)65 mT E)93 mT

Question

Quizplus · Accepted Answer

The magnetic field just outside one end of a bar magnet can be approximated by the formula for the magnetic field at the end of a solenoid, $B = \frac{\mu_0 m}{2\pi R^3}$, where $m$ is the magnetic dipole moment, $R$ is the radius of the magnet, and $\mu_0$ is the vacuum permeability constant ($4\pi \times 10^{-7} \, \text{Tm/A}$). Substituting the given values, $m = 2.0 \, \text{A}\cdot\text{m}^2$ and $R = 0.01 \, \text{m}$, we get $B = \frac{(4\pi \times 10^{-7}) \times 2.0}{2\pi \times (0.01)^3} = 40 \, \text{mT}$.

A Cylindrical Bar Magnet of Radius 1