What is the width of the second slit in a single-slit diffraction experiment?

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Homework Statement

In a single-slit diffraction pattern on a flat screen, the central bright fringe is 1.37 cm wide when the slit width is 3.48E-5 m. When the slit is replaced by a second slit, the wavelength of the light and the distance to the screen remaining unchanged, the central bright fringe broadens to a width of 1.88 cm. What is the width of the second slit? It may be assumed that θ is so small that sinθ ∼ tanθ.

Homework Equations

The Attempt at a Solution

 

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You have to provide the relevant equation and your attempt to solve the problem.

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