# TG4-CIE112.pdf - CIE 112 - Fundamentals of Surveying...

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CIE 112 - Fundamentals of SurveyingTeachers’ Guide Module #4Name:_________________________________________________________________Section: ____________Schedule:________________________________________Class number:_______Date:________________This document is the property ofPHINMA EDUCATION1Lesson title:Earth’s Curvature and RefractionLesson Objectives:At the end of this module, you will be able to:1.Apply the earth’s curvature and refraction correction.2.Determine whether it is an obstruction or a clearanceat a certain point according to the line of sight.Materials:Calculator, Pen, PaperReferences:Roy, S.K. (1999).Fundamentals ofSurveying. New Delhi: PrenticeHall of India Private LimitedSchofield, W. & Breach, M.(2007).Engineering Surveying.Burlington, Canada: Elvesier Ltd}A.LESSONPREVIEW/REVIEW1)Introduction (2 mins)Have you ever tried mountain climbing or experienced to be on the top of a tall building?If you already did, you could say that as you go higher your line of sight will extend to thehorizon. It is due to the earth’s curvature that conceals the view but already seenas yougo to a higher altitude. On the other hand, refraction of light is the bending of lightdownwards as it passes through different layers of air with varying densities. Whenmeasuring short distances, these effects can be neglected but working with surveys in longsights requires these two to be considered. Because errors yielded from these phenomenaincreases with distance. For precise work these errors need to be calculated and correctionswill be applied for accurate data.Due to the curvature of the earth, the points of measurement appear to be lower thanthey actually are. In refraction of light, the points appear to be higher than the actually are.The effect of curvature is always greater than that of refraction. Thus, the combined effectof these two causes the points of measurement to be lower than its true quantity.2)Activity 1: What I Know Chart, Part 1 (3 mins)What I KnowQuestions:What I Learned (Activity4)Research using different means of resources. Learning thesame topic using different methods at the same time will helpyou to acquire more detailed ideas and widen yourunderstanding.
CIE 112 - Fundamentals of SurveyingTeachers’ Guide Module #4Name:_________________________________________________________________Section: ____________Schedule:________________________________________Class number:_______Date:________________This document is the property ofPHINMA EDUCATION21.Horizontal line departsfrom a level surfacebecause of __?2.How to eliminate the effectof earth’s curvature andrefraction?3.In long sights, thehorizontal line of sightdoesn’t remainstraight butit slightly bendsdownwards havingconcavity towards earthdue to __?B.MAIN LESSON1)Activity 2: Content Notes (13 mins)Vertical Lineis a line that follows the local direction of gravity as indicated by a plumbline.

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Term
Summer
Professor
rexan
Tags
sea level, PHINMA Education