A current loop with radius 20 cm and current 2 A is in a uniform magnetic field of 0.5 T. Considering all possible orientations of the loop relative to the field, what is the largest potential energy difference (in Joules) you can find between two orientations?

Answer 1

ΔPE=Work
W=∫τ•dφ=∫pBsinφ•dφ=
=∫IABsinφ•dφ=∫Iπr²Bsinφ•dφ=
=Iπr²Bcosφ (limits of integral are π/2 and 0)= Iπr²B

W=Iπr²B=2•π•0.2²•0.5=0.125 J

Answer 2

.125 J is wrong answer. can you check lease. thanx