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Unformatted text preview: MASSACHUSETTS INSTITUTE OF TECHNOLOGY 2.71 Optics Spring 09 Problem Set #1 Posted Feb. 9, 2009 Due Wednesday, Feb. 18, 2009 1. Spherical waves and energy conservation We mentioned in class that the amplitude of the electric field describing a plane wave remains constant as the wave propagates, thereby guaranteeing conservation of energy. Using the same argument and the fact that the power (in Watts) is proportional to the square of the electric field amplitude, show that the amplitude of a spherical wave should decay like 1 /r as function of distance r from the source of the spherical wave. 2. Order of magnitude calculations The solar irradiance data in W / m 2 for the radiant energy by the sun incident outside the earths atmosphere are given by the following plot : ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SOLAR_IRRADIANCE/irrad031202.jpg a) How many commercially available light bulbs placed at 1m away from the atmospheres edge would generate the same amount of irradiance on an area...
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This note was uploaded on 02/24/2012 for the course MECHANICAL 2.710 taught by Professor Sebaekoh during the Spring '09 term at MIT.
- Spring '09