Consider the following statement:

1. Magnetic energy density is directly proportional to the square of the magnetic field.
2. Magnetic energy density is inversely proportional to the square of the magnetic field.

Which of the following statement is CORRECT?

CONCEPT:

• Electric fields are produced by two kinds of charges, positive and negative. 
• Magnetic fields are associated with two magnetic poles, north and south, although they are also produced by charges (but moving charges). 
  • Magnetic field points in the direction of the force experienced by a north pole.

EXPLANATION:

• The energy per unit volume, which is the instantaneous energy density uB associated with a magnetic field is given by:

\(\Rightarrow {u_B} = \frac{1}{2}\frac{{{B^2}}}{{{\mu _o}}}\)

• From the above, it is clear that energy density is directly proportional to the magnetic field B2. Therefore option 1 is correct.

Additional Information

• The energy per unit volume, which is the instantaneous energy density uE associated with an electric field is given by:

\(\Rightarrow {u_E} = \frac{1}{2}{\epsilon_0}{E^2}\)