What is the energy density in the magnetic field 25 cm from a long straight wire carrying a current of 12 a? (μ0 = 4π × 10-7 t · m/a) what is the energy density in the magnetic field 25 cm from a long straight wire carrying a current of 12 a? (μ0 = 4π × 10-7 t · m/a)?

Explanation:

First of all, we need to calculate the magnetic field magnitude at 25 cm from the wire, which is given by

where

μ0 = 4π × 10-7 t · m/a is the vacuum permeability

I = 12 A is the current in the wire

r = 25 cm = 0.25 m is the distance from the wire

Substituting,

Now we can calculate the energy density of the magnetic field, which is given by

And substituting, we find

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

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