Question

How much energy is stored in a solenoid 45.0 cm long, 9.0 cm diameter having 800 turns when 22.0 A of current flows through it?

A. 2.75 J

B. 3.95 J

C. 4.78 J

D. 5.48 J

Answer 1

₀ = 4π × 10⁻⁷ H/m

= magnetic permeability in free space.

and further relation below

U = 1/2 x {( ₀ . N² A ) / L } x I²

where N = number of turns

A = area of the solenoid

L = length of the solenoid

I = current flowing through the solenoid

so the correct option is

A). 2.75 J