Problem 3
Monochromatic light of wavelength passes through two narrow slits separated by onto a screen distance away, with . Find the fringe spacing and position of bright fringe order from the central maximum, using the small-angle approximation. Assume the string, pulley, electrical source, or optical apparatus is ideal as stated, and neglect any effect not specified. State a clear sign convention, identify the physical Keep one model and sign convention throughout. Reuse each intermediate result with the same convention, then check that the answer has the required physical dimensions. (a) Set up the physical relation. (b) Find an intermediate quantity. (c) Obtain the answer and check its conditions and units.
problems.proof.stepOf
problems.proof.analysis
The difference is independent of order, so the fringes are equally spaced. This is consistent with the stated model and the chosen sign convention.
problems.proof.pitfall. The small-angle approximation requires the far-screen geometry and yields spacing, not a dimensionless ratio.