I am having some problems with this problem I was able to ge

I am having some problems with this problem. I was able to get part A correct but i got part B wrong i have attached the work i have done for this problem i am unsure what i have done wrong the second part of this problem.

Problem 22.01 Part A In the two-slit experiment, monochromatic light of frequency 5.00 1014 Hz passes through a pair of slits separated by 2.20 x 10-5 m. (c 3.00x108 m/s) (a) At what angle away from the central bright spot does the third bright fringe past the central bright spot occur? 4.69 Submit Mv Answers Give Up Correct Part B (b) At what angle does the second dark fringe occur? 2.34 Submit My Answers Give Up Incorrect, correct answer displayed

Solution

you have to multiply it by 2