PHYSICS 7C Midterm: physics7C-fa2011-mt2-Aganagic-exam
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Each problem is worth 10 points, for a total of 40 points. If you are asked to substitute a result from a previous part, which you were not able to solve, please clearly de ne a variable to stand in for your would-be solution to the previous part. Read all questions carefully before answering: consider an array of 4 evenly spaced antennae, all lying on one line, with distance d between each one (see figure 1). All antennae act as point sources, and emit radio waves (wavelength ) in phase with one another. Very far away there is a long line of radio detectors (essentially a screen) parallel to the line of the emitting antennae. Ignore the phasor rotation with respect to time. Draw the rst phasor starting at the origin and pointing along the x-axis of your diagram. Start the next phasor at the tip of the rst one and so on.
