What is the differential equation governing the growth of current in the circuit as a function of time after t=0? express the right-hand side of the differential equation for di(t)dt in terms of i(t), vb, r, and l?

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?