Check Your Understanding
From , the interference maximum occurs at for From Equation 4.1, this is also the angle for the second diffraction minimum. (Note: Both equations use the index m but they refer to separate phenomena.)
Conceptual Questions
Walkie-talkies use radio waves whose wavelengths are comparable to the size of the hill and are thus able to diffract around the hill. Visible wavelengths of the flashlight travel as rays at this size scale.
The diffraction pattern becomes two-dimensional, with main fringes, which are now spots, running in perpendicular directions and fainter spots in intermediate directions.
The parameter is the arc angle shown in the phasor diagram in Figure 4.7. The phase difference between the first and last Huygens wavelet across the single slit is and is related to the curvature of the arc that forms the resultant phasor that determines the light intensity.
No, these distances are three orders of magnitude smaller than the wavelength of visible light, so visible light makes a poor probe for atoms.
UV wavelengths are much larger than lattice spacings in crystals such that there is no diffraction. The Bragg equation implies a value for sinθ greater than unity, which has no solution.
Image will appear at slightly different location and/or size when viewed using shorter wavelength but at exactly half the wavelength, a higher-order interference reconstructs the original image, different color.
Problems
a. , , , ; b. , , , ; c. Decreasing the number of lines per centimeter by a factor of x means that the angle for the x-order maximum is the same as the original angle for the first-order maximum.
Additional Problems
a. 42.3 nm; b. This wavelength is not in the visible spectrum. c. The number of slits in this diffraction grating is too large. Etching in integrated circuits can be done to a resolution of 50 nm, so slit separations of 400 nm are at the limit of what we can do today. This line spacing is too small to produce diffraction of light.
a. 549 km; b. This is an unreasonably large telescope. c. Unreasonable to assume diffraction limit for optical telescopes unless in space due to atmospheric effects.