Question

A current carrying loop is placed in a uniform magnetic field in four different orientations, I, II, III and IV. If we arrange them in decreasing order of potential energy, then

I II.

III. IV.

• A. I > III > II > IV
• B. I > II > III > IV
• C. I > IV > II > III
• D. III > IV > I > II

Answer 1

Answer: (C)

I > IV > II > III

Answer 2

U = – MB cos q

U_I = – MB cos 180⁰ = + MB

U_II = –MB cos 90⁰= 0

U_III = –MB cos (Acute angle) = –ve

U_IV = –MB cos (Obtuse angle) = +ve

̃ I > IV > II > III