Question

State Ampere's circuital law. Use this law to obtain the expression for the magnetic field inside anair cored toroid of average radius 'T', having 'n' turns per unit length and carrying a steady current I. Show that the magnetic field in the open space inside and exterior to the toroid is zero.
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Answer 1

Answer:

ccording to Ampere's circuital law, the line integral of magnetic field induction along a closed curve is equal to the total current passing through the surface enclosed in the closed curve times the permeability of the medium.

∮  

B

.  

dl

=μ  

o

​  

I  

enclosed

​  

 

Applying ampere's law for the given toroid,

B(2πr)=μ  

o

​  

NI

But, N=2πrn

B=μ  

o

​  

nI

(b)

The observer sees south pole as shown in the attached figure.

Magnetic moment due to a loop is given by:

m=iA

For N turns,  i=NI

m=NIA

Explanation: