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pat666

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## Homework Statement

6. A solenoid 25.0 cm long with a cross-sectional area of 0.500 cm2 has 400 turns of wire and carries a current of 80.0 A. Calculate:

a) the magnetic field in the solenoid;

b) the energy density in the magnetic field if the solenoid is filled with air. (2 marks)

## Homework Equations

## The Attempt at a Solution

n=400/.25=6000turns per metre

[tex] B=\mu_o*n*I[/tex]

[tex]B=0.16T [/tex]

I'm not sure if this is right? I didn't use the area and am not sure about my calculation for n.

[tex] u_B= 1/2*{B^2}/{\mu_o} [/tex]

so [tex] u_B=63999.99999 [/tex]

I need someone to check my procedure please and also what are the usints for energy density, J?

Thanks