Which formulas are appropriate for calculating intensity?

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The discussion focuses on calculating the intensity ratio of an interference pattern created by monochromatic plane waves. The relevant formula provided is I=I0(cos(∏(d/(λL)z)), with specific values for wavelength, slit spacing, and distance to the wall. Participants clarify the importance of correctly identifying parameters such as d, L, and λ, and emphasize the need to compute the ratio I/I0. There is a correction noted regarding the exponent in the formula, which is crucial for accurate calculations. Overall, the conversation aims to guide the calculation of intensity ratios in a double-slit interference setup.
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Homework Statement


Monochromatic plane waves of wavelength 537nm are incident on two narrow slits and produce an interference pattern on a wall 3.1m away. The slits are spaced 26 micrometers apart and are 5.7 micrometers wide each. What is the ratio of intensity to that of the central fringe a distance of 35.5mm from the central fringe?
2. Relevant equation

I=I0(cos(∏(d/(λL)z))

The Attempt at a Solution



I tried using this formula to find the intensity of the central fringe and also the intensity of the fringe 35.5mm from the central fringe, however, I could not determine what I(sub)naught was.
 

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Your formula is correct, as you have it in the link. You left out the exponent of 2 when you typed it out. They simply want you to compute the ratio ## \frac{I}{I_o} ##. You should be able to do that using your formula. (Usually the letter ## x ## is used instead of ## z ## in this formula. In any case, ## z=35.5 ## mm). You should be able to figure out what ## d ##, ## L ## and ## \lambda ## are.
 
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Charles Link said:
Your formula is correct, as you have it in the link. You left out the exponent of 2 when you typed it out. They simply want you to compute the ratio ## \frac{I}{I_o} ##. You should be able to do that using your formula. (Usually the letter ## x ## is used instead of ## z ## in this formula. In any case, ## z=35.5 ## mm). You should be able to figure out what ## d ##, ## L ## and ## \lambda ## are.
That makes so much sense! Thanks a lot for your time!
 
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