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7.1 Acoustic pressure at a distance from a source. A jet engine on the ground generates a
sound power density level of 155 dB at a distance of 10 m from the engine. Assume that
the sound travels uniformly in all directions in
An outdoor thermometer uses a bimetal strip to sense and display temperature.
It is based on the fact that different metals expand at different rates in
response to temperature, hence the strip bends at a rate that depends on the
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4.1 Optical quantities. An isotropic light source (a source that radiates uniformly in all
directions in space) produces a luminance of 0.1 cd/m2 at a distance of 10 m. What is the
power of the source?
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