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| =°

Answer

given,

wavelength (λ) = 650 nm

angle = 5°

using bragg's law

d = 7.46 x 10⁻⁴ cm

number of slits per centimeter

  =

b) wavelength of two rays  650 nm and 420 nm

     d =  2 x 10⁻6 m

    we now,

for 650 nm

θ = 40.54°

for 450 nm

θ = 24.83°

now, difference

|θ_{650} -θ_{420}| =40.54°-24.83°

|θ_{650} -θ_{420}| =19.71°

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)