4) (introduction) As we will leam next DL, visible light is comprised of oscillating electric and magnetic fields. Because the universe is tlnee dimensional and these oscillations are transverse, for every' traveling ray of light there are two independent directions in which the electric field can be oscillating. At the end of last DL, you should have picked up 3 pieces of polarizing filter in class. The polarizing filter absorbs light whose electric field is oscillating in one of these tvvo directions while allowing light whose electric field is oscillating in the perpendicular direction to pass. Thus, light that is unpolarized initially will end up polarized after passing through the filter. The direction of the resulting polarized light is called the polarization axis. a) Look flu-ough apolalizer at a light source and rotate the polarizer through 1800. Use your observation to explain how you know that the light source is unpolalized. b) Look at the same light source through two polarizers held close together or touching. Now keeping one fixed, rotate the other slowly through 3600. Roughly plot the brightness of the light coming tlnough both polarizers as a function of the angle of rotation. Explain the variation in blightness in tenns of polarization and the action of the tvvo polarizers. c) With two polarizers placed together and tumed so minimum light is transmitted, add a third polarizer in benveen the two other polarizers. Always keep the two original polarizers tumed so they transmit minimum light. Tum the third polarizer through 900. Note down what you obsewe and fry to develop an explanation for your result. (Hint: superposition tells us that E-fields add to produce a total E-field so we could say that any E-field can be thought of as a sum of E-fields oscillating in other directions.)