1 | Draw a ray diagram showing why a small light source (a candle, say)
produces sharper shadows than a large one (e.g. a long fluorescent bulb).
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2 | A Global Positioning System (GPS) receiver is a device that lets you
figure out where you are by exchanging radio signals with satellites. It
works by measuring the round-trip time for the signals, which is related to
the distance between you and the satellite. By finding the ranges to several
different satellites in this way, it can pin down your location in three
dimensions to within a few meters. How accurate does the measurement of
the time delay have to be to determine your position to this accuracy?
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3 | Estimate the frequency of an electromagnetic wave whose wavelength is
similar in size to an atom (about a nm). Referring back to book 4, in what
part of the electromagnetic spectrum would such a wave lie (infrared,
gamma-rays,...)?
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4 | The Stealth bomber is designed with flat, smooth surfaces. Why would
this make it difficult to detect via radar?
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5 |
The large figure shows a curved (parabolic) mirror, with three parallel
light rays coming toward it. One ray is approaching along the mirror's
center line. (a) Photocopy the diagram (or download the book and print
out this page) and continue the light rays until they are about to undergo
their second reflection. To determine the angles accurately, you'll want to
draw in the normal at the point where the ray hits the mirror. What do you
notice? (b) Make up an example of a practical use for this device. (c) How
could you use this mirror with a small lightbulb to produce a parallel beam
of light rays going off to the right?
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6 |
The natives of planet Wumpus play pool using light rays on an elevensided
table with mirrors for bumpers. Trace this shot accurately with a
ruler to reveal the hidden message. To get good enough accuracy, you'll
need to photocopy the page (or download the book and print the page)
and draw in the normal at each place where the ray strikes a bumper. | |