Q. Coherent light with wavelength 609 passes through two very narrow slits, and the interference pattern is observed on a screen a distance of 3.00 from the slits. The first-order bright fringe is a distance of 4.84 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. Two football players are intially 20m/s apart. The first player (a receiver) runs perpendicularly to the initial line joining the two players at a constant speed of 7.0 m/s. After two seconds, the second player (the quarterback) throws the ball at a horizontal speed of 15 m/s (ignore any vertical motion).In what horizontal direction should the quarter back aim so that the ball reaches the same spot the receiver will be? At what time will the ball be caught?