Common Detailed Writng


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here u can got the detail about some of the commom instruments u used in commonly ever physics practicals in B.Sc labs

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Common Detailed Writng

  1. 1. Trisha Banerjee_bhu @2010
  2. 2. Ramsden’s eyepiece Trisha Banerjee_bhu @2010
  3. 3. An eyepiece is a magnified designed to give more perfect image than obtained by single lens. Construction of Ramsden’d eyepiece:- This eyepiece consists of two plano convex lenses with their convex faces turned inwards and separated by a distance equal to 2/3 f where f is their common focal length . The lens facing the field is called the field lens and the other close to the eye is called the eye lens. Why Ramsden’s eyepiece is used with telescope:- Because in it, cross wires are fitted outside the eyepiece and hence mechanical adjustments and measurement are easily possible. Where are cross wires situated:- when the instrument is in normal position the cross wire lie at f/4 in front of the field lens. It is the place where the real image is formed by the objective of the telescope. there are another type of eye piece is HUYGEN’S eyepiece. Trisha Banerjee_bhu @2010
  4. 4. Screw Gauge Sleeve(Mai anvil spindle n scale) Thimble(Cir Rachet Space to cular scale) knob put the object frame Trisha Banerjee_bhu @2010
  5. 5. Trisha Banerjee_bhu @2010
  6. 6. MSR = 5.2 + CSR = 42 MSR = 5.2 +CSR = 28 Trisha Banerjee_bhu @2010
  7. 7. Jaws ( measure Vernier Callipers inner Screw dimension) clamp Main scale Vernier scale Jaws ( measure outer dimension) Trisha Banerjee_bhu @2010
  8. 8. Trisha Banerjee_bhu @2010
  9. 9. Spectrometer Trisha Banerjee_bhu @2010
  10. 10. Spectrometer :- it is an impt instrument used for the study of spectra produced by the prism and gratings, for the measurement of the dispersive powers , wavelength of spectral line s, the refractive indices of solid and liquids , etc. The essential parts are:- 1)collimator 2) turn table 3) telescope Trisha Banerjee_bhu @2010
  11. 11. Collimator source Vertical Achromatic convex adjustable lens slit Sliding tube Trisha Banerjee_bhu @2010
  12. 12. Setting of the collimator and the telescope Trisha Banerjee_bhu @2010
  13. 13. Collimator:- It is a fixed horizontal metallic tube fitted with an achromatic convex lens L1 at one end. At the other end it carries a shorter coaxial tube which slides inside the longer tube. The end of the shorter tube carries a vertical slit of adjustable width. The distance between the slit and the lens L1 can be altered by a rack and pinion arrangement . The collimator is also provided with leveling screws. Trisha Banerjee_bhu @2010
  14. 14. Turn Table Turn table Vernier scale Screw to rotate the turn table Vernier scale minutely Lock the telescope Lock the turn table Trisha Banerjee_bhu @2010
  15. 15. Turn Table:- It is a circular table provided with a platform G on which the prism is placed . The platform can be raised to a suitable height and can be rotated along with the turn table about the axis of the spectrometer . The rotation of the table can be measured by noting the position of two vernier V1 and V2 on a circular scale. Parallel lines and concentric circles are drawn on the platform . They help in placing the prism in the desired position . The platform is provided with three leveling screws , while the table is provided with clamping and tangent screws. Trisha Banerjee_bhu @2010
  16. 16. Telescope Achromatic Ramsdens’s convex lens Sliding eyepiece tube Screw for adjusting the length for focusing Trisha Banerjee_bhu @2010
  17. 17. Telescope:- It is a horizontal metallic tube having an achromatic convex lens L2 at one end . At the other end it carries a shorter coaxial tube containing cross wires . Within this tube slides another small tube containing a Ramsden’s eyepiece . The distance between the lens L2 and the cross wires can be altered with a rack and pinon arrangement while that between the cross wires and the eyepiece can be altered by hand . The telescope can be rotated about the axis of the spectrometer and is provided with leveling screws as well as with clamping and tangent screw. Its position can be read on the circular scale.( which is attached to it) by means of verniers V1 and V2. Trisha Banerjee_bhu @2010
  18. 18. Trisha Banerjee_bhu @2010
  19. 19. Ballistic galvanometer:- galvanometer:- Trisha Banerjee_bhu @2010
  20. 20. Inner structure of galvanometer Trisha Banerjee_bhu @2010
  21. 21. Brief construction :- The ballistic galvanometer is usually employed to measure the quantity of charge flowing in a given circuit due to transient current. it consists of a coil of copper wire wound on a non conducting frame which is suspended by a phosphor bronze strip between the poles of strong permanent magnet horse – shoe shape magnet . In order to increase the magnetic flux in the gap , the cylindrical soft iron – core is placed with in the coil. The pole pieces of the magnet are cylindrical concave in shape so that the magnetic field is radial in the narrow annular gap and is also perpendicular to the coil surface . The whole apparatus is covered in a shell to avoid disturbance from outside .Three leveling screws are provided below the base of the galvanometer . The deflection of the coil is measured by lamp and scale arrangement . Note:- When large damping is present , the motion of the coil is non oscillatory and the moving coil galvanometer become dead beat . The construction and working of such a galvanometer is different from moving coil galvanometer. Trisha Banerjee_bhu @2010
  22. 22. Digital multimeter Trisha Banerjee_bhu @2010
  23. 23. A digital multimeter:- Multimeters contain Ohmeters, Voltmeters, Ammeters and a variety of capabilities to measure other quantities. AC and DC voltages are most often measurable. Frequency of AC voltages. Multimeters also feature a continuity detector, basically an Ohmmeter with a beeper if the multimeter sees less than 100 Ω then it beeps otherwise it is silent. This is very useful for finding whether components are connected when debugging or testing circuits. Multimeters are also often able to measure capacitance and inductance. This may be achieved using a Wien bridge. A diode tester is also generally onboard, this allows one to determine the anode and cathode of an unknown diode. A LCD display is also provided for easily reading of results. Trisha Banerjee_bhu @2010
  24. 24. Screen ( contains the eyepiece) Ramsden’s eyepiece Main scale Leveling the reading vertical Micrometer height of reading the screen Trisha Banerjee_bhu @2010