Question

What is a continuous spectrum? What is a discrete spectrum? What kind of light source produces each type of spectrum? A diffraction grating has a grating spacing of d - 1500nm. It is used with light of wavelength 500 nm. What angle will the first-order diffraction image be seen? The grating used in the lab (a) can produce only images in the horizontal (b) must be rotated in its holder until it produces the desired vertical pattern (c) produces images only in the vertical direction (d) produces only images to the left of the slit A diffraction grating with d-2000 nm is used with a mercury discharge tube at a distance 50.0 cm from the slit. What is the distance y from the slit to the first order image for the blue- green wavelength of mercury? 1. 2. 3. 4. 5,

Answer 1

Answer : (1)

A continuous spectrum is a frequency plot usually resulting from an analog filtering and computation technique. A discrete spectrum is usually the result of a digital computation, most often an FFT (Fast Fourier Transform). There are advantages and disadvantages to each. One requirement of the FFT is that anti-aliasing filtering must be applied to the analog data before it is digitized

Let me put it this way: in the radio frequency spectrum, broadcasting has a discrete spectrum, since each station broadcasts at its assigned frequency. Noise has a continuous spectrum; it’s not regulated, and you hear it no matter where you tune your receiver to (until you tune to a station that’s strong enough to overcome it).

I should admit that this is an oversimplification, because each station, as it modulates its radiation to convey energy, spreads its radiation over a small range within which the spectrum is continuous. But there are still gaps between different stations (or should be), so in that sense the spectrum is discrete.

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