A point source of light is submerged 2.0 m below the surface of a lake and emits rays in all directions. On the surface of the lake, directly above the source, the area illuminated is a circle. What is the maximum radius that this circle could have? Take the refraction index of water to be 1.333.

The maximum radius that this circle is r=2.685m

Explanation:

The circle on the surface will exit the total reflection occurs

on the point the angle of reflection 90°

The critical angle for air water interface is:

The radius of circle on the surface is AO.From geometry

The maximum radius that this circle is r=2.685m

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-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

-with the above experiment, the first geothermal plant in usa started in 1922 with a capacity of 250 kilowatts

-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

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