The energy stored in the magnetic field at a solenoid 30

The energy stored in the magnetic field at a solenoid 30 cm long and 3 cm diameter wound with 1000 turns of wire carrying a current at 10 A, is ________ Joules

1. 0.148 or 0.15 Joules
2. 11.148 or 11.2 Joules
3. 10.120 or 10.15 Joules
4. None of the above

L =	N²μ₀A	=	10⁶ × 4π × 10^-7 × (π / 4) × (9 × 10^-4)
	l		0.3

=	9π² × 10^-5
	0.3

∴ Energy =	1	LI² = 0.148 or 0.15 Joules
	2