4. Given that the single slit width b = 1.0 x 10- m and the lens focal length f = 0.50 m, the monochromatic parallel light of A1 = 400 nm and A2 = 760 nm is used to illuminate vertically respectively. (1) Calculate the distance from the first level bright fringe of the two lights to the center of the screen and the distance between the two bright fringes. (2) If the single slit is replaced by a grating engraved with 1000 lines per centimeter, calculate the distance from the first bright fringe of the two monochromatic lights to the center of the screen and the distance between these two bright fringes?

4. Given that the single slit width b = 1.0 x 10- m and the lens focal length f = 0.50 m, the monochromatic parallel light of A1 = 400 nm and A2 = 760 nm is used to illuminate vertically respectively. (1) Calculate the distance from the first level bright fringe of the two lights to the center of the screen and the distance between the two bright fringes. (2) If the single slit is replaced by a grating engraved with 1000 lines per centimeter, calculate the distance from the first bright fringe of the two monochromatic lights to the center of the screen and the distance between these two bright fringes?