Exam Bank Solution Manual for Interference and optical fibres Already Passed

Exam Bank Solution Manual for Interference and optical fibres Already Passed define path difference - Answers difference in distance travelled by two waves define phase difference - Answers the fraction of a complete cycle between two points on a wave/ between 2 waves what is a coherent source - Answers has same frequency and wavelength with a fixed phase difference what is diffraction - Answers the spreading out of waves over a gap how does increasing the wavelength of the source change the way it diffracts? - Answers increases the amount of diffraction central maximum becomes wider intensity decreases how does increasing the slit width of the source change the way it diffracts? - Answers decreases the amount of diffraction central maximum becomes narrower intensity increases what happens if the slit is made smaller than the wavelength of he source - Answers most of the waves are reflected off of the slit what is a diffraction grating - Answers a slide containing equally spaced slits, very close together. what are the benefits to a diffraction grating - Answers produces a much sharper and brighter pattern since more rays of light are reinforcing the pattern so measurements are more accurate Explain why more fringes will be seen if each of the slits is made narrower, assuming that no other changes are made - Answers narrower slits make more diffraction there will be more interference so more fringes are seen the fringes will be the same width if white light is used and you are looking at the 1st order fringe, what colour in the spectra will be closest to the central maxima and what will be furtherst - Answers violet is closest because has shortest wavelength and diffracts the least therefore red will be furtherst since it has the longest wavelength how are light fringes formed - Answers when the light meets in phase and interferes constructively . this occurs when the path difference between the waves is a whole number of wavelengths what is the refractive index of a material as a property - Answers measures how much light slows down as it enters the new density material for the equation n = c/cs what is cs and what is c - Answers cs = the speed of light in the material c = the speed of light in a vacuum what can you say about the density of a material if it has a high refractive index - Answers it optically very dense what is the refractive index of air - Answers 1 what is refraction - Answers when waves enter a different medium, causing them to slow down and change direction if the light slows down, what can you say about how it bends and the density of the new material it enters - Answers the new material is more optically dense/ has a higher refractive index the light bends towards the normal what happens when the angle of refraction is 90 degrees - Answers the light is refracted along the boundary the angle of incidence is now at the critical angle what is total internal reflection - Answers a material is refracted back into the material, due the the angle of incidence exceeding the critical angle what condition must be satisfied for total internal reflection - Answers the refractive index of the first material must be greater than the second material describe the structure of an optical fibre - Answers optically dense core surrounded by cladding of lower optical density how can signal degradation occur - Answers absorption dispersion what is absorption of a signal - Answers where part of the signal's energy is absorbed by the