1. Use diffraction equation on page 369. Rearrange and solve for theta: theta is the angle whose sin equals the wavelength times the order of the image (1 in this case), divided by the distance between the lines on the diffraction grating. For all of these problems you will have to solve for d, the distance between the lines. If there are 5800 lines per cm, how far between two lines?
3. Use same equation, but no need to rearrange, simply plug and chug. Don't forget, this is a second order image. To find the color, refer to plate VII in the color section in the middle of the text.
4. Harder problem. Like #1, you have to find the diffraction angle for a certain wavelength of light. The distance to the image screen and the distance over from the center to the first order image on the screen are related through the diffraction angle and right triangle geometry (see Fig. 15-7). Refer to Plate VII again for the wavelengths of each end of the visible spectrum.
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