Question

(a) A simple telescope demo: We need to build this from scratch. We have an eyeglass lens to get started, which we could use as our eyepiece lens; we would need to buy an objective lens and a cardboard tube (from our favorite online marketplace). Assuming the eyeglass lens is a converging one and has focal length f, what type of objective lens do we need if we would like the telescope to have a magnification factor of 100? What length cardboard tube do we need for the telescope housing? What is a simple experiment (or set of experiments) we can do to determine the focal length of the eyeglass lens and whether this is a concave or convex lens? (b) An interferometer demo: A Michelson interferometer demo already exists within the physics department, and is already set up, but the laser it uses, with 7 = 590 nm, is broken. The demo supply closet has another laser that works but the wavelength is 1090 nm. Could we use the interferometer demo with the 1090 nm laser? If so, what would we expect to be different, and in what way, when using the demo with the 1090 nm instead of 590 nm laser? (c) An X-ray crystallography demo: We have neither the budget nor the safety measures in place for using an actual X-ray source and crystal for this demo, but luckily we have access to scrap materials from a kitchen that is being renovated! In that kitchen, there is a microwave (which still works!), a bunch of aluminum foil, and (fortuitously!) a large supply of polystyrene. This is great! We can set up a “scaled up" version of X-ray crystallography by making a fake crystal using a large polystyrene block, in which we embed aluminum foil balls representing the crystal atoms, arranged in an appropriately-sized lattice representing the array of atoms in the crystal. We can then use microwaves as fake X-rays. A microwave receiver and speaker can then be used to demonstrate 2 or 3 orders of diffraction maxima when the microwaves are directed at some angle theta relative to the normal of the fake crystal. How big should the polystyrene block be, and what should be the spacing of the aluminum foil balls? (We can assume that the microwave is monochromatic, i.e. it emits a single wavelength, with = 12.2 cm.)

Answer 1

Given data that, = > A simple telescope demo: - Assuming an eye glass lens is a conversing end has focus length f, What type of objective lens do we need if we would like the telescope to have magnification factor of = > We get, Eye glass lens is convex lens (converging lens) . Its focal length can be determined simply by the focusing a distant object, the distance of real image formed on screen from lens is equal to focal length of lens (distant object method) In normal mode magnification is equal to ratio of focal lengths . Hence for magnification of 100 . The focal length of new conversing lens to be order should have a focal length 100 times the focal length of Eye lens . The length of card board the is equal to sum of focal length i . e, 101 times the focal length of eye lens .