Comments on WebWork #10

 

Note: since Greek letters are miserably troublesome  to  insert here, I'm using Q ='theta' and W = 'lambda'; also

C = constructive; D = destructive interference.

 

 
 

#4.  You are given the wavelengths [W, here; see above!!!] for C and D.

The applicable equations are 24.9 and 24.10.  The difficulty in solving this problem is that you don't know 'm' .
To find m, solve the two equations simultaneously for m, using the W's for C and D interference. Then use m in the appropraiate equation to find t.

Hint:  If you come up with negative values for m,  note that for C, you could equally well use 2 nt = [m - 1/2]W

#'s 5 and 6.   Look at the figure for #6; this general pattern is applicable to any diffraction question.  Use the method of equation 24.4 to relate the displacement on a screen [from center of central max to the minima] in terms of Q.

#5.The diffraction equation 24.11 is for D [minima] only. So for the distance between two maxima [C], find an equivalent separation distance in terms of the extant minima, noting that the C peaks are halfway between the D minima.

#6.  Use the plot to figure out displacement; from that and  screen distance determine Q.  Then use that in the diffraction equation to find W.  Note that the answer is to be in microm, NOT nanom!!!!!!