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°

c) up

hope this

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west