Question $3$

$4$ points

$($CLO$-4)$ A rectangular coil of width $2\mathrm{.}3$ cm and length $6\mathrm{.}9$ cm has $990$ turns and carries a current of $8\mathrm{.}0$ A $.$ It is placed in a magnetic field of $0\mathrm{.}54$ T $.$ Initially, the coil's magnetic moment makes an angle of $56$ with the magnetic field. What is the change of the coil's potential energy $(U=U_{\text{f}\text{i}\text{n}\text{a}\text{l}}-U_{\text{i}\text{n}\text{t}\text{i}\text{a}\text{l}})($in unit $"J"($Joule$))$ when it rotates from the initial position to the position where its magnetic moment is parallel to the magnetic field?

Enter your answer as algebraic $($positive or negative$)$ decimal number with $2$ digits after the decimal point. Don't enter the unit $\text{'}$J$".$

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