26.45. Set Up: Maxima are located by where is the angle of incidence and d is the separation of crystal planes. Solve: (a) First maximum, so (b) For For the equation has no solution. Reflect: Since is not small, we find that for and there are only two angles for which constructive interference occurs. 26.46. Set Up: The maxima are given by Solve: (a) and This is an x ray. (b) The equation doesn’t have any solutions for 26.47. Set Up: Rayleigh’s criterion says where s is the distance of the object from the lens and Solve: Reflect: The focal length of the lens doesn’t enter into the calculation. In practice, it is difficult to achieve resolution that is at the diffraction limit. 26.48. Set Up: The diffraction is by a single slit of width a , not by a circular aperture. The diffraction minima are located by and Rayleigh’s criterion is where s is the distance of the object from the lens and Solve: 26.49. Set Up: Rayleigh’s criterion for circular apertures says Solve: (a) (b) (c) (d)
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