Experiment 10 on optical physics to determine cauchy constant PDF

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Summary

To determine the Cauchy’s constant of the given prism using Spectrometer, prism, prism clamp, Magnifying glass, mercury vapor lamp, etc....

Description

Experiment -10 Aim:To determine the Cauchy’s constant of the given prism.

Apparatus: Spectrometer, prism, prism clamp, Magnifying glass, mercury vapor lamp, etc.

Theory: Cauchy's equation is an empirical relationship between the refractive index and wavelength of light for a particular transparent material. It is named for the mathematician Augustin-Louis Cauchy, who defined it in 1836. The most general form of Cauchy's equation is

The refractive index n of the material of the prism for a wavelength λ is given by.

Where A and B are called Cauchy’s constants for the prism. If the refractive indices n1 and n2 for any two known wavelengths λ1 and λ2 are determined by a spectrometer, Cauchy’s constants A and B can be calculated from the above equation.

Observation Observations: s: For Angle of Prism: Reading of Reflected ray from

Vernier 1

Vernier 2

MSR

VSR

TOTAL

MSR

VSR

TOTAL

FACE 1 (say a)

304

22

304.22

123

92

123.92

FACE 2 (say b)

63

84

63.84

243

88

243.88

Difference between a and b

119.62

119.96

A=59.895 degree ~ 60degree

Pair of colors

λ1 x10-9 m

λ2 x10-9 m

n1

n2

A

B

Yellow and Blue

579.1

435.8

1.48

1.49

1.37

0.036

Green and Violet

546.7

404.7

1.48

1.49

1.46

0.036

MEAN

1.415

0.036

Colour

λ x10-9 m

(1/λ2) x1 x10 012 m

n

Yellow

579.1

2.988

1.483

Green

546.7

3.353

1.485

Blue

435.8

5.265

1.491

Violet

404.7

6.103

1.499

Result: From Calculations: A= 1.415 B= 3.677 x 10-9 From Graph: A= 1.477 B= 0.041 x 10-9...