KCET2016PhysicsMagnetic Effects of Current
A long solenoid with ( 40 ) turns per cm carries a current of ( 1 ~A ). The magnetic energy stored per unit volume is ( J m⁻³ ).
Options
- A( 3.2 )
- B○ ( 32 ) п
- C( 1.6 ) п
- D( 6.4 )
Correct answer
A. ( 3.2 )
Step-by-step solution
Given, number of turns ( =40 ) turns per ( cm ); current ( =1 ~A ) Therefore, magnetic energy stored per unit volume ( = 1 2 ₀ n² I² ) [ array l = 1 2 (4 10⁻⁷ ) (40 10² )² (1)² = 4 4 4 _ 10⁻⁷ 10⁵ 2 =32 10⁻¹=3.2 array ] Thus, magnetic energy stored per unit volume ( =3.2 IJ m ⁻³ )