The magnetic energy stored in a current carrying solenoid is (if B = magnetic field, l = length of solenoid, A = area of cross section of solenoid) :
Answer & explanation
Correct answer: option 4
Energy density of the magnetic field is given by
$ u = \frac{B^2}{2\mu_0}$
Magnetic field energy of magnetic field is $ U = uV = \frac{B^2}{2\mu_0}Al$