• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Pathlength Difference from two waves

  • Thread starter skibum143
  • Start date
1. Homework Statement
Two slits separated by a distance of d = 0.12mm are located at a distance of D = 780mm from a screen. The screen is oriented parallel to the plane of the slits. The slits are illuminated by a coherent light source with a wavelength of lambda = 549E-6 mm. The interference pattern shows a peak at the center of the screen (m=0) and then alternating minima and maxima.
7. [1pt]
What is the pathlength difference between the two waves from the two slits at the first (m=1) maximum on the screen?

2. Homework Equations
d*sintheta = m*wavelength
sintheta = y(dist bt two maxima) / D(distance to screen)

3. The Attempt at a Solution
I'm really confused about what the "pathlength difference" refers to. It doesn't specify it in the book. I know the angles take different paths to get to the same point because of the distance inbetween them, but is it asking for an angle???
I solved the problem for y using the above equations, and at the first maxima (m=1), y(distance between the two maxima) is 0.0036m. But I don't know where to go from there?
So....I think I just realized that pathlength difference refers to "m", but what are the units??
Ah, just figured it out...you have to use "m" and multiply it by the wavelength.

Related Threads for: Pathlength Difference from two waves


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