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A uniform magnetic field B of 0.3 T is along the positive Z-direction.  A rectangular loop (abcd) of sides 10 cm×5 cm carries a current I of 12 A.  Out of the following different orientations which one corresponds to stable equilibrium ?


  • Option 1)

  • Option 2)

  • Option 3)

  • Option 4)


Answers (1)


As we learnt in 

Magnetic moment (M) -


- wherein

N-number of turns in the coil 

i-current throughout the coil 

A-area of the coil 





Current loop as a magnetic dipole -

A current carrying circular coil behaves as a bar magnet whose magnetic monent is M

- wherein


 Magnetic moment of current carrying rectangular loop of Area A is given by M= NiA


Magnetic moment of current carrying coil is a vector and its direction is given by right hand thumb rule,

For rectangular loop,

\vec{B} at centre due to current in loop and  \vec{N} are always parallel


Option 1)

This is incorrect option.

Option 2)

This is incorrect option.

Option 3)

This is correct option.

Option 4)

This is incorrect option.

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