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Cornus Interference Apparatus

Model: HO-ED-INT-02

This device is similar to Newton's Rings apparatus, except that an arrangement for loading the test piece is provided for carrying out Cornus interference studies. The objective of this experiment is to determine Poisson's ratio and Young's Modulus for different materials (glass, Perspex etc) using interference method. Weights are positioned at both ends of the bar, causing it to bend longitudinally downward. A glass plate is placed on the bar to produce an interference pattern. By examining the interference pattern, extent of longitudinal and lateral bending can be determined. Thus, Poisson ratio and Young's modulus of the bar can be deduced.

When a plano-convex lens rests on a uniformly bent glass bar, an air film is formed between the two surfaces. Without adding any mass in the weight hanger we get circular rings. But as we uniformly add mass on the weight hangers, the beam bends and we get elliptical fringes.


Experiment Examples

To study the elastic constants of glass by Cornus interference methods,


i.    Hyperbolic fringes

When a rectangular glass plate rests on a uniformly bent glass beam, an air film is formed between the two glass surfaces. On illuminating the air film with monochromatic light, two conjugate systems of hyperbolic fringes (longitudinal and transverse) around the point of contact of the glass plates are obtained.

By measuring the longitudinal and transverse curvature, Young’s modulus (Y) and Poisson’s ratio (σ) can be determined.



ii.    Elliptical fringes

When a plano-convex lens rests on a uniformly bent glass bar, an air film is formed between the two surfaces. On illuminating the air film with monochromatic light, a system of elliptical fringes (longitudinal and transverse) around the point of contact of the glass bar is obtained.

By measuring the longitudinal and transverse curvature, Young’s modulus (Y) and Poisson’s ratio (σ) can be determined.



Fig. Arrangement for Cornus experiment

Specifications    (Travelling Microscope)

    Magnification : 10 X

    Micrometer travel : 25 mm

    Least count : 0.01 mm



Related Topics

    Young's Modulus

    Poisson's ratio

    Rigidity Modulus

    Bulk Modulus
Features

    In this apparatus, sodium vapor lamp and spectral LED's are used as light sources

    Traveling microscope with precision micrometer is used for accurate measurements

    High quality optics are used in order to get the clear fringe pattern

    All materials used in this setup are of laboratory grade and are corrosion resistant
Scope of Supply


    Travelling Microscope with Rigid Base

Model No: ED-INT-02-TMRB
Magnification
:
30 x
Micrometer Travel
:
25 mm
Least Count
:
0.01 mm
Quantity
:
1 no.
Travelling Microscope with Rigid Base

    Knife Edges with Rigid Base

Model No: ED-INT-02-KERB
Height
:
180 mm
Material
:
Anodized Aluminum Alloy & SS
Quantity
:
1 no.
Knife Edges with Rigid Base

    LED Mount with Rigid Base

Model No: ED-INT-02-LEDM
Height
:
225 mm
Material
:
Anodized Aluminum Alloy & SS
Quantity
:
1 no.
LED Mount with Rigid Base

    Weight Hanger Clamp

Model No: ED-INT-02-WHC
Length
:
5 mm
Material
:
Anodized Aluminium Alloy
Quantity
:
2 nos.
Weight Hanger Clamp

    Weight Hangers with Weights

Model No: ED-INT-02-WHW
Material
:
Brass
Weights
:
100 gm & 50 gm
Quantity
:
2 Sets each
Weight Hangers with Weights

    Plano Convex Lens

Model No: ED-INT-02-PCL1000
Material
:
Borofloat
Diameter
:
50 mm
Focal Length
:
1000 mm
Quantity
:
1 no.
Plano Convex Lens

    Plano Convex Lens

Model No: ED-INT-02-PCL750
Material
:
Borofloat
Diameter
:
50 mm
Focal Length
:
750 mm
Quantity
:
1 no.
Plano Convex Lens

    Optical Flat

Model No: ED-INT-02-OF
Material
:
Borofloat
Diameter
:
50 mm
Thickness
:
2 mm
Quantity
:
1 no.
Optical Flat

    Beamsplitter Plate

Model No: ED-INT-02-BSP
Material
:
Borofloat
Diameter
:
45 x 45 mm
Thickness
:
2 mm
Quantity
:
1 no.
Beamsplitter Plate

    Sodium vapor lamp with Power Supply

Model No: ED-INT-02-SLPS
Output Power
:
35 W
Quantity
:
1 no.
Sodium vapor lamp with Power Supply

    LED's with Power supply

Model No: ED-INT-02-LEDP
Colours
:
Red, Blue, Green, Yellow
Out put
:
5V, 800 mA
Quantity
:
1 no. each
LED's with Power supply

    Test Samples

Model No: ED-INT-02-TS
Material
:
Borofloat glass, PMMA
Diameter
:
300 x 40 x 2 mm
Quantity
:
1 no. each
Test Samples

    Accessories

Dust Protective cover
Instruction Manual

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