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The illustration shows a circle with dot at the center is labeled, arm 1. Another circle with cross at the center is labeled, arm 2. The direction of magnetic moment makes an angle theta with the loop’s surface normal n caret. The direction of the force F sub 1 on the arm 1 is upward and the direction of the force F sub 2 on the arm 2 is downward. A line connects the arms whose center point is at the origin O. The distance of the arms from the origin is start fraction a over 2 end fraction. The moment arms are of magnitude left parenthesis a over 2 right parenthesis sine theta.