sextant deepali jain's group (1)
Post on 27-May-2015
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- 1. Submitted by:Supervised by:-Deepali Jain Dr. Pranav SaxenaDevendra Kumar SharmaDilip Kumar MeenaSubmitted to:Dheerendra maharya Physics Department, Jagannath Gupta Institute of(E&C A), B- tech, Ist Year Engineering and Technology
2. SEMINAR COVERS1. Object2. Apparatus3. Description of sextant4. Principle5. Theory6. Procedure7. Observations8. Calculations9. Result10. precautions 3. ObjectTo Determine the height of a given object byusing Sextant 4. Apparatus :Sextant 5. What is Sextant ?A sextant is a navigational instrument used tomeasure the angle of elevation of celestialbodies, usually the sun or moon, in order todetermine ones location and direction.More generally, a sextant can be used tomeasure the angle between any two objects, bywhich we can calculate the distance betweenthem. 6. Parts of a Sextant 7. Index mirror: large polished plate that reflects light.Telescope: optical instrument made of lens that magnifiesobjects.Telescope clamp: reinforcing circle.Eyepiece: lens the user looks through.Telescope printing: lens adjustment.Frame: structure that serves as the base for the differentparts of the sextant.Graduated arc: graduated edge of the arc. 8. Locking device: apparatus that holds the sextant in place.Drum: graduated button used to take measurements.Index arm: type of ruler that determines direction ormeasures an angle.Screw to regulate small mirror: piece of metal used toadjust the horizon mirror.Glass filter: colored transparent substance.Horizon mirror: small polished glass plate that reflectslight.Glass filter: colored transparent substance. 9. Principle of Sextant:Sextant is based on the principle of rotationof a plane mirror . According to thisprinciple, When a plane mirror is rotatedthrough an angle , the reflected angle is rotates through an angle 2 provided thatthe incident ray remains unchanged 10. Theory :Let H be the height of the water tank MQ whose height is to bedetermined. Take a refreance point P on MQ at a height hr above groundPQ = MQ MP = H hr = hLet and be the angles subtended by the PQ height at Fand E , distance apart.PE.. cot = PQ PE = h cot . PQ = h PFSimilarlycot = . PF = h cot PQ 11. . X = Pf PE= h ( cot cot )h= X.cot cot . Actual height of water tank H = h + hrH= X.+ hr ( cot cot ) 12. Procedure:1. Find the least count of the vernier attached with the indexarm.2. Draw a horizontal line P as a reference line on the pillar ofthe water tank.3. Look at the horizontal line P through the transparentportion of the horizon glass plate M2 by telescope fromsome distance (say 10 m) from the water tank keeping theplate of the arc scale of sextant vertical .4. Rotate the index arm towards zero of the scale till directimage of reference line P coincides with the image of thesame reference line through the polished portion of horizonglass plate M2 13. 5. Now rotate the index arm away from zeroreading till the image of the top Q of water tankin the mirror M2 coincides with the image of thereference line P seen directly through the glassplate M2 .6. take 3 sets of the observations at differentdistances. 14. Observations:Least count of circular scale = 1Least count of micrometer screw = 1Least count of vernier scale : 1/5 = 60/5= 12"Height of Sextant from ground hr = 5 ft 15. Observation table:-Sr. Distance Zero Reading (a)Elevation reading (b) Angle ofno.M.S C.S. V.S. Total M.S. C.S. V.S total elevation . = b-a1. 7m333 2" 3.5612 26 2" 12.41 = 8.862. 9m319 2" 3.317 10 38 2" 10.63 = 7.3173. 11 m327 3" 3.459 31 2" 9.51 = 6.066 16. Calculations:(i) x = 9m 7m = 8.866= 2m = 7.317 h1 =x.2 . = = 1.485 mcot - cot7.787 6.415(ii)x = 11m 9m = 6.066=2m = 8.866 h2 =2 . = 1.233 m 9.433 - 7.787 17. (iii) x = 11m 7m = 6.066 =2 = 8.8664. H3 == 1.325 m9.433 - 6.415 h1+ h2+ h3 . = 1.347m(H) mean = 3 1.347 x 3.28 ft = 4.42 ftH = hr + H= 5 + 4.42 ft = 9.42 ft 18. Result: Height of water tank is 9.42 ft Calculated height- Actual height x 100% error = Actual height =9.42 9.00 x 100= 4.7%9.00 19. Precautions:1. Plane of index arm should be parallel to the moving arm and normal to the plane of the circular arc.2. At the position of zero reading both mirrors M1 and M2 should be parallel to each other.3. While taking reading the plane of the fixed arm and index should be kept vertical.4. The telescope should be directed towards the centre of horizon glass M2.