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student07
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Homework Statement
a) Imagine that you are conducting an activity with a laser to create an interference pattern. Use the appropriate equations to predict two ways (other than the way described in the following example) to change the interference pattern in order to have closer fringes. Explain your predictions.
The example they give is : Δx = Lλ/d
the distance between the fringes (Δx) is proportional to the wavelength (since they are both numerators). This means that increasing one will increase the other. Therefore, decreasing the wavelength will decrease the distance between the fringes. (Hint: You can use the "Thomas Young's Double-slit Experiment" simulation to verify predictions).
b) If you were using a hands-on activity to verify your predictions and use measurements to determine the wavelength of the laser being used, describe any safety precautions you would take and sources of error that you might encounter. Be sure to explain how you might reduce the effects of the sources of error.
2. The attempt at a solution
a) One way is using:
mλ = d sinθm for maxima or (n-1/2)λ = d sinθn for minima
d would represent the separation between fringes, where the distance of the fringes can be found for a nodal or antinodal line at a given angle.
Another way is:
mλ = d Xm / L for maxima or (n-1/2)λ = dXn / L for minima
the distance of the fringes is proportional to the distance of the slit to the screen (L); thus, decreasing the distance between the screen to where the laser is being projected on, decreases the distance between the fringes.
b) Wearing the correct safety goggles will diminish chances of damaging the retina; thus pointing laser at a person's face is not recommended. If using a laser beam do not leave uncovered after use.
A source of error could be the dot of the laser, since the experiment is not done in a vacuum, the light is spread out making it difficult to get an accurate measurement. If measured with a ruler then the reflection of the laser might be deceiving since the user might not read the exact wavelength or the ruler might not make an accurate horizontal with the surface the laser is reflected on. This could be solved by taking all the appropriate distances measurements from the reflection point to the fringe location and solve for the points where the laser is reflected on. Any suggestions are appreciated thank you