Question

A current of 1.0 A is established in a tightly wound solenoid of radius 2 cm having 1000 turns/metre. Find the magnetic energy stored in each metre of the solenoid.

Answer 1

Magnetic Energy Stores is $7.9 \times 10^-^4$ J

Explanation:

i = 1.0A, r = 2cm, n = 1000turn/m  

• Magnetic energy stored = $B^2V/2\mu_0$  

• Where B → Magnetic field, V → Volume of Solenoid.

= $\frac {\mu_0n^2i^2}{2\mu_0} \times \pi r^2h$

= $\frac {4\pi \times 10^-^7 \times 10^6 \times 1\times \pi \times 4 \times 10^-^4 \times 1}{2}$ [h = 1 m]

= $8 \pi^2 \times 10^-^5$

= $78.956 \times 10^-^5$

= $7.9 \times 10^-^4$ J