Nuclear fusion provides the energy source for stars including the Sun. a) Describe what happens during nuclear fusion.
b) A nebula may evolve into a main sequence star, such as the Sun.
Explain how a nebula may evolve into a main sequence star. (6)
I need 6 clear points or in a paragraph

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?