DP 71 (50 points) [This problem is pertinent to Section 23-2 of the Textbook.] A layer of oil (with n, -1.45 ) floats on water (with n, -1.33.) A ray of light shines onto the oil with an incidence angle of 8, -40.0 degrees with the normal, as shown in the figure. Suppose that the index of refraction for the air is n - 1.00. Air Find the angle of refraction, say , . when Coil the light ray enters the water. Waller (Note that the angle of refraction , should be measured with respect to the normal.) DP 7.2 (50 points) [This problem is pertinent to Section 23-3 of the Textbook.] A ray of light, emitted beneath the surface 13.4 om of an unknown liquid with air above it, undergoes total internal reflection as shown in the figure. The critical angle of incidence is depicted and called 8, in this 15.0 cm figure. The index of refraction for the air is 7, -1.00. What is the index of refraction , for this unknown liquid?DP 6.1 (50 points) A parallel-plate capacitor has square plates that have edge length equal to 0.500 m and are separated by 2.00 mm. It is connected to a battery and is charged to 20.0 V. How much energy is stored in this capacitor? DP 6.2 (50 points) (a) You want to store 5.00x10" Cof charge on a capacitor, but you only have a 100-V voltage source with which to charge it. What must be the value of the capacitance? (b) You want to store 2.50x10"* J of energy on a capacitor, but you only have a 100-V voltage source with which to charge it. What must be the value of the capacitance