Try out some of the principles of light by comparing Polaris tothe sun.
a. The intensity of sunlight at a satellite in earth orbit is1360 W/m2. What is the magnitude of the electric and magnetic field?
b. Astronomers estimate the distance to Polaris is 431 lightyears and its intrinsic luminosity (energy per second) is 2200times that of the sun. Use proportional reasoning and your answerto part a to estimate the intensity and the magnitude of theelectric field at the earth. You can give it in terms of A.U.,factors of earth’s distance from our sun.
c. A planet in the “habitable zone” around Polaris shouldreceive a light intensity similar to our planet. Again useproportional reasoning to estimate what distance might be a goodone.
d. The color of a star depends on temperature of the outerregions of the star. The peak wavelength for polaris is 400 nm andfor the sun is 500 nm. Another famous star, Betelgeuse, has itspeak wavelength at 828 nm. What color light are these specificwavelengths, and what is the frequency of this light? Actually, weperceive the first two stars to be “white” and Betelgeuse to bedistinctly “red”. Explain in your own words.
