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Trisha Banerjee_bhu @2010

Ramsden’s eyepiece


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.


Screw Gauge

Sleeve(Main scale)

Thimble(Circular scale)

RachetknobSpace to

put the object

spindleanvil

frame


MSR = 5.2 + CSR = 42 MSR = 5.2 +CSR = 28


Main scale

Vernierscale

Screw clamp

Jaws ( measure inner dimension)

Jaws ( measure outer dimension)

Vernier Callipers


Spectrometer


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 table3) telescope


Vertical adjustable slit

source

Achromatic convex lens

Sliding tube

Collimator


Setting of the collimator and the telescope


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.


Turn table

Vernier scale

Vernierscale

Lock the telescope

Lock the turn table

Screw to rotate the turn table minutely

Turn Table


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.


Achromatic convex lens Ramsdens’s

eyepiece

Screw for adjusting the length for focusing

Sliding tube

Telescope


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’seyepiece . 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 V 2 .


Ballistic Ballistic galvanometer:galvanometer:--


Inner structure of galvanometerInner structure of galvanometer


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.


Digital multimeter


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.


Ramsden’seyepiece

Main scale reading

Micrometer reading

Leveling the vertical height of the screen

Screen ( contains the eyepiece)


common detailed writng

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tube trisha banerjee

turn table trisha banerjee

objectframetrisha banerjee

spectrometertrisha banerjee

field lens

shorter tube

eye lens

cross wires