Question

The magnetic field at a point located
at a distance r from the center of a
toroid of inner radius a and outer
radius b is proportional to
Select one or more:
Or
1/r
Or?
0
1/r2​

Answer 1

r

1

=0.25 m,r

2

=0.26 m,n=3500,I=11 A

(a)magnetic field outside is zero. It is non zero only inside the core of a toroid.

By definition, Ampere's Law states that integration of magnetic field over an amperian loop is equivalent to constant μ multiplied by current enclosed. Now, the current that flows at outer circumference and inner circumference of toroid are in opposite direction to each other. Therefore, current enclosed by Amperian loop is zero. Thus, magnetic field outside the toroid is zero.

(b)Magnetic field inside the core of a toroid is given by the relation

B=

l

μ

o

nI

l=length of toroid

where, l=2

2

π(r

1

+r

2

)

=.51π .

B=

0.51π

4π×10

−7

×3500×11

so, B=3×10

−2

T

(c)Magnetic field in the empty space surrounded by the toroid is zero as there will no current in the empty space.