# Diffraction grating problem, missing orders, diffraction minimum and maximums.

#### NCyellow

1. Homework Statement
Missing orders occur for a diffraction grating when a diffraction minimum coincides with an interference maximum. Let D be the width of each slit and d the separation of slits. (a) show that if d = 2D, all even orders (m=2,4,6) are missing. (b) show that there will be missing orders whever d/D = m1/m2. where m1 and m2 are integers. (c) Discuss the case d + D, the limit in which the space between slits becomes negligible.

2. Homework Equations
sin(theta) = m(lamda)/d

3. The Attempt at a Solution
I figured out that in order for there to be a missing order m1 and m2 needs to coincide. However, setting m1D=m2d (m2 can't be 0), plugging in the given information d=2D, I simply get m2=m1/2. That did not seem to prove anything. Please give me some hints.

Related Introductory Physics Homework Help News on Phys.org

#### Redbelly98

Staff Emeritus
Science Advisor
Homework Helper
You'll need to use the equation for diffraction from a single slit also.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving