A magnetic needle suspended parallel to a magnetic field requires 
of work to turn it through 
. The torque needed to maintain the needle in this position will be
A
B
C
D
Text Solution
Verified by ExpertsThe correct answer is:
B
Work done in changing the orientation of a magnetic needle of magnetic moment 
in a magnetic field 
from position 
to 
is given by
Here, 
(i)
The torque on the needle is
In magnitude,
Dividing (ii) by (i), we get
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