1. The problem statement, all variables and given/known data Two optically flat plates of glass are separated at one end by a wire of diameter 0.210 mm; at the other end they touch. Thus, the air gap between the plates has a thickness ranging from 0 to 0.210 mm. The plates are 15.0 cm long and are illuminated from above with light of wavelength 570.0 nm. How many bright fringes are seen in the reflected light? 2. Relevant equations 2t = (m + ½)λ (constructive) m = 0, 1, 2, … t = thickness of the air wedge λ = wavelength in vacuum (air) 3. The attempt at a solution Pretty darn clueless on this one. I don't think the above equation is even proper. I'm lost on what to do with the plethora of values they give you, and can't understand how to fit them into ANY of the equations I've been mulling through. Since we are looking for bright spots, then clearly we are dealing with constructive interference, but I'm quite lost after that. Any help greatly appreciated. Thanks in advance!