A device called a Fabry–Perot interferometer contains two parallel mirrors as shown in Figure P25.23. Multiple reflections occur between the inner mirror surfaces, and the waves emitted at the top can interfere. Assume the light waves travel nearly perpendicular to the mirrors, the emitted waves interfere constructively, and the spacing between the mirrors is exactly 3.5 mm. What is a possible value for the wavelength in the visible range between 600 and 700μm?