Light of wavelength 650 nm is normally incident on the rear of a grating. the first bright fringe (other than the central one) is at an angle of 5 ° with respect to the normal.

1)find the number of slits per centimeter in the grating.

/cm

2)two rays of light of wavelength 650 nm and 420 nm are normally incident on a different grating. if the grating has 5000 slits/cm, what is the angular seperation of of the two light rays' second order maximum.

|θ650 -θ420| =°

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?