NEET Physics Magnetism and Matter Questions Solved

NEET - 2012

A magnetic needle suspended parallel to a 

magnetic field requires 3 J of work to turn

it through 60°. The torque needed to maintain 

the needle in this position will be

(a) 23J                      (b) 3 J

(c) 3 J                       (d) 32 J

Concept Videos :-

#3 | Magnetic Dipole Moment & Field due to Bar Magnet
#4 | Superposition of Magnetic Field due to Bar Magnet
#5 | Field due to Short Bar Magnet
#6 | Torque Acting on Bar Magnet in Uniform Field
#7 | Work Done in Rotating Dipole in Field & PE
#8 | Oscillations of Bar Magnet in Uniform Field
#9 | Solenoid as Equivalent Bar Magnet

Concept Questions :-

In this case, work done

W=MB(cosθ1-cosθ2)    =MB(cos 0°-cos 60°)    =MB1-12=MB2MB=23J                      (so, given W=3J)τ=MB sin 60°=(23)32J=3J

Difficulty Level:

  • 23%
  • 43%
  • 22%
  • 13%
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