A laboratory compares the performance of two devices that have exactly the same slit…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
A laboratory compares the performance of two devices that have exactly the same slit separation d=2.0μm and are illuminated by red light of wavelength λ=640nm.
Device A: a traditional double-slit (2 slits).
Device B: a transmission grating fabricated on a 1.0mm-wide substrate containing 500 equally spaced, parallel slits.
(a) Calculate the angle θ1 of the first-order principal maximum (m=1) for each device.
(b) For each device, determine the angular half-width of the central (zeroth-order) maximum, defined as the absolute value of θ at which the intensity first falls to zero on either side of the central peak.
(c) Compute the ratio of the central-maximum widths (double-slit to grating) and interpret the result in terms of each device’s ability to distinguish closely spaced wavelengths.