Measuring the wavelength of light using diffraction

[ScienceGirl]

This is a repost from the general physics forum, as I didn't see the homework help forum before I posted in the other place.

Anyway, I did an experiment last week in my college physics class where we measured the wavelength of a laser light using single, double, and multiple slit diffraction and diffraction grating. Using the measurements and Young's equation, we calculated the wavelength of the light. My teacher said that as we use more slits, we should get more accurate results. Can someone explain why this happens? Is is just because as you add more slits the maxima get narrower and brighter so they are easier to see and measure?

 

[ShawnD]

It's because the more slits you have, the more lines it makes for the same distance. If yo have 1 slit, it makes 1 line. If you have 5000 slits (and the light goes through all of them), you get about 5000 lines.

It's sort of like finding how people feel about something. If you ask 10 people, you'll get really half-assed results. If you ask 10000 people, you'll get fairly accurate results.

 

[M98Ranger]

Yes, as you add more slits, the diffraction pattern becomes more complex and the interference effects become more pronounced. This means that the bright and dark fringes become more distinct and easier to measure accurately. Additionally, with more slits, the distance between the fringes decreases, making it easier to measure small changes in the fringe positions. This leads to more precise measurements and a more accurate calculation of the wavelength using Young's equation.