1. The problem statement, all variables and given/known data Find the angular radius of the tenth bright fringe in a Michelson interferometer when the central-path difference (2d) is (i) 1.50 mm and (ii) 1.5 cm. Assume the orange light of a krypton arc is used and that the interference is adjusted in each case so that the first bright fringe forms a maximum at the centre of the pattern. 2. Relevant equations 2d sin theta = m lambda or 2d cos theta= m lamda 3. The attempt at a solution i confuse to use the equation. theta= cos-1 or sin -1 (6057 armstrong x 10th) divide 1.50mm the answer that i get is not logic.