Magnetism and Matter

Topics in this chapter

• Bar Magnets and Magnetic Moments
• Magnetic Dipoles in External Fields
• Earth Magnetism and Angle of Dip
• Magnetic Materials and Susceptibility
• Ferromagnetism and Hysteresis

Cheat sheet

Practice questions

1. Question 1Q-F1B84A

   A short bar magnet of magnetic moment $M$ is placed with its axis making an angle of $30^\circ$ with a uniform magnetic field of magnitude $B$. The potential energy of the magnet is:

   1. A.-MB/2
   2. B.-MB \sqrt{3}/2
   3. C.MB/2
   4. D.MB \sqrt{3}/2
   See the answer and solution
2. Question 2Q-4F7A0A

   The magnetic susceptibility ($\chi$) of a paramagnetic material varies with absolute temperature ($T$) as:

   1. A.\chi \propto T
   2. B.\chi \propto T^2
   3. C.\chi \propto 1/T
   4. D.\chi is independent of T
   See the answer and solution
3. Question 3Q-47CC68

   If a magnetic material is placed in a non-uniform magnetic field, it experiences:

   1. A.Only a force
   2. B.Only a torque
   3. C.Both a force and a torque
   4. D.Neither force nor torque
   See the answer and solution
4. Question 4Q-BA3DF1

   The horizontal component of Earth's magnetic field at a place is $3.6 \times 10^{-5}\text{ T}$ and the angle of dip is $60^\circ$. The magnitude of the Earth's magnetic field at this place is:

   1. A.1.8 \times 10^{-5}\text{ T}
   2. B.3.6 \times 10^{-5}\text{ T}
   3. C.7.2 \times 10^{-5}\text{ T}
   4. D.7.2 \times 10^{-4}\text{ T}
   See the answer and solution
5. Question 5Q-C6DB53

   A bar magnet of magnetic moment $M$ is cut into two equal pieces transverse to its length. The magnetic moment of each new piece will be:

   1. A.M
   2. B.M/2
   3. C.2M
   4. D.M/4
   See the answer and solution