Simple high school experiment. According to Δy=λD/a, where D is the distance between the screen and the double slit, Δy is the distance between fringes, λ is the wavelength of laser light, and a is the separation of the double slit. All variables except a are known. The aim of the experiment is to find out the value of a. I got an experiment result with an error of 3%. Can the error be further reduced?phinds said:What research have you done so far? What have you found out? What school level is this for?
Almost certainly, but first you will have to figure out where it is coming from. How accurate are your distance measurements? How confident are you that the wavelength is what you expect?Jason Ko said:Can the error be further reduced?
The wavelength is told, it seems that the only error came from the measurement of Δy and D.Nugatory said:Almost certainly, but first you will have to figure out where it is coming from. How accurate are your distance measurements? How confident are you that the wavelength is what you expect?
And how are they being measured? By what instruments exactly, and what is the error/tolerance for those devices?Jason Ko said:The wavelength is told, it seems that the only error came from the measurement of Δy and D.
simply ruler measuredphinds said:And how are they being measured? By what instruments exactly, and what is the error/tolerance for those devices?
And you have not answered the most important question that I asked:Jason Ko said:simply ruler measured
what is the error/tolerance for those devices?
That is fair, but I don't see anyone proposing a full error analysis with quadrature addition and derivatives and the like either.Ibix said:To be fair, if @Jason Ko is at high school (as implied) it's more than possible that he hasn't been taught what is needed for a decent error analysis.
Try thinking out of the box. If someone asked you to measure the thickness of some sheets of paper, what could you do to get the best accuracy if all you had was a ruler with 1mm markings on it? Likewise if they asked you to find the spacing between threads on a bolt, what would be a 'good' strategy'? And why?Jason Ko said:I wonder how I can reduce the experiment error. So what can I do?
To reduce the impact of external vibrations, you can use a vibration isolation table or an optical bench with vibration damping features. Additionally, conducting the experiment in a quiet, stable environment away from heavy machinery or foot traffic can help minimize vibrations.
Using a coherent light source such as a laser can significantly improve the accuracy of the experiment. Lasers produce monochromatic and coherent light, which ensures well-defined and stable interference patterns compared to incoherent light sources like incandescent bulbs.
To ensure proper alignment of the slits, use a high-quality double slit apparatus with precisely manufactured slits. Additionally, you can use a micrometer or a fine adjustment mechanism to carefully align the slits with the light source. Verifying the alignment by observing the initial interference pattern can also help make necessary adjustments.
The width and separation of the slits are crucial for generating clear and distinct interference patterns. Using slits with a small and consistent width and a precise separation distance will produce more accurate and well-defined fringes. Experimenting with different slit dimensions can help optimize the pattern visibility and accuracy.
To accurately measure the fringe spacing, use a high-resolution screen or detector to capture the interference pattern. Employing a digital camera with image analysis software can provide precise measurements of fringe spacing. Additionally, using a ruler or a micrometer scale placed parallel to the screen can help in obtaining accurate measurements manually.