Permanent magnetismHard
Question
The earth′s magnetic field at a given point is 0.5 × 10-5 Wb m-2. this field is to be annulled by magnetic induction at the centre of a circular conducting loop of radius 5.0 cm. The current required to be flown in the loop is nearly
Options
A.0.2A
B.0.4A
C.4A
D.40A
Solution
Fields created at the centre
= 0.5 × 10-5 Wb/m2
Due to current in circular loop, field created in the centre =
=
= 0.5 × 10-5
i =
= 0.3980 = 0.4A
= 0.5 × 10-5 Wb/m2
Due to current in circular loop, field created in the centre =

=
= 0.5 × 10-5i =
= 0.3980 = 0.4A
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