Q.Coherent light with wavelength 598 nm passes through two very narrow slits, and the interference pattern is observed on a screen a distance of 3.00 {rm m} from the slits. The first-order bright fringe is a distance of 4.84 {rm mm} from the center of the central bright fringe. For what wavelength of light will the first-order dark fringe be observed at this same point on the screen?

Q. A diverging lens (f = -12 cm) is located 20.0 cm to the left of a converging lens (f = 35.0 cm). A 3.00 cm tall object stands to the left of the diverging lens, exactly at its focal point.