When you look at a distant star or planet, you are looking back in time. How far back in time are you looking when you observe Pluto through the telescope from a distance of $ 91 x 10 12 ? O a. 19700s O b. 0.000051s O c. 1.77 x 10*21s O d. 1.7x10^10sThe speed of light in plastic is 1.64 x 10'm / 3- What is the index of refraction of the plastic? (Remember: the speed of lingt $ 3 0 x 10"m /8. O a. 0.55 O b. 1.83 O c. 4.92 x 10*16 O d. 1.83 x 10*16Sallie is at the beach and enjoying the sun. The frequency of the UV light that causes her to tan is 7 80 x 10 14 Hz. What is the wavelength of this UV light. (Remember: speed of light is 3 0 x 10"m / s O a. 2630000 m O b. 3.8 x 10*-7m O c. 2.68 x 10*23 m O d. 23.67 mA popular lawn ornament in the 1960s was a colored reflecting sphere that sat in the yard as a decoration. If a bird is 10.0cm from the blue reflecting sphere and sees its image reflected -5.0cm behind the sphere, what is the focal length of the spherical reflector? O a. 7.5 cm O b. 15cm O c. - 10 cm O d. -15 cmPolly applies her mascara while looking in a concave mirror whose focal length is 18cm. She looks into it from a distance of 12cm. How far is Polly's image from the mirror? O a. 15 cm O b. -15 cm O c. - 36 cm O d. -7.5 cmA friend is wearing a pair of mirrored sunglasses whose convex surface has a focal length of -20.0cm. If your face is 40.0cm from the sunglasses, how far behind the sunglasses is your image? O a. -13.3 cm O b. -40 cm O c. 20 cm O d. -10 cm