Aphysics professor wants to show an interference pattern made by shining a laser on two thin slits that are separated by a distance of o.075 mm. the professor knows that she cannot get the interference pattern large enough to show to her class by just placing the slits 7 m away from the wall, so she asks her colleagues for advice. one colleague seems to remember that another professor, who retired several years ago, used to do a similar demonstration and sends the first professor to the demo room to see what she can find. the professor finds a piece of equipment that seems to be what she is looking for. a translucent screen is connected to a metal bracket that can hold two lenses. one lens is located about 10 cm from the screen and the second lens could be placed anywhere from 5 cm to 15 cm in front of the first lens (farther away from the screen) on an adjustable arm. the professor figures that an interference pattern could be made on one side of the translucent screen and the lenses could form a system that allows the final image to be projected on a distance wall or screen. a quick measurement of the first lens indicates that it has a focal length of -17 cm assume that the physics professor has a variety of lasers available to use for this demonstration. the apparatus will be placed on a table 7 m away from the wall upon which she wishes to display the projected interference pattern. (the laser is separate from the screen/lens apparatus but it will sit on the same table.) the professor decides that an interference pattern with a distance of about 75 cm between the two m- 2 bright fringes will be easy enough for her entire class to see (a) determine the focal length of the second lens that could make the demonstration work. (b) the professor cannot find a lens with that focal length that fits in the bracket on the ap- paratus the one that the retired professor used must have broken years ago! she decides to call in a favor to a friend from graduate school that now works at an optics fabrication shop. what should her "order" be? (consider the lens maker's equation) c) how many times larger is the projected interference pattern than one that could be made with just the slits alone? assume that the intensity of the image is enough for it to be seen easily note: there are many possible answers to this problem depending on choices that you? ve made be sure to clearty state any assumption that you?