Light of wavelength 600 nm illuminates a diffraction grating. The second-order maximum is at angle 39.2. How many lines per millimeter does this grating have?

Diffraction equation applies in this case:

d*Sin x = m*wavelength, where d = spacing of lines, x = angle = 39.5°, m = order of maximum = 2

Substituting;

d* Sin 39.5 = 2*600*10^-9

d = (2*600*10^-9)/Sin 39.5 = 1.88656*10^-6 m

In 1 mm (or 0.001 m), the number of lines is given as;

Number of lines = 0.001/d = 0.001/(1.88656*10^-6) = 530.065 ≈ 530 lines

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.