Before we can use parallax to measure the distance to a nearby star, we first need to know: ?
a. the distance to the nearest star besides the sun
b. the month in which the star is observed
c. the earth-sun distance
d. the sun's mass

Light from two different sources are incident upon the same side of a polarizing filter. light from one source is polarized with total intensity ip, while light from the other source is unpolarized with total intensity iu. as you rotate the polarizing filter through 360 degrees, the intensity of the transmitted light on the other side varies by a factor of 9. what is the relative intensity of the initial polarized source to the unpolarized source, or ip/iu?