The expression for the magnetic energy stored in a solenoid in terms of magnetic field \(B\), area \(A\) and length \(l\) of the solenoid is:
1. | \( \dfrac{1}{\mu_0}B^2Al\) | 2. | \( \dfrac{1}{2\mu_0}B^2Al\) |
3. | \( \dfrac{2}{\mu_0}B^2Al\) | 4. | \( \dfrac{3}{2\mu_0}B^2Al\) |
The ratio of magnetic energy per unit volume and electrostatic energy stored per unit volume in a parallel plate capacitor is: