ARC SPECTRUMAIM To photograph the arc spectrum of Iron and Brass and identify the spectral lines

APPARATUS Constant deviation spectrometer, power supply, sharpened rods of iron & brass, imaging system.

THEORY AND PROCEDUREArc spectrum is a spectrum formed form light produced by an electric arc, characteristic of the gas or vapor through which the arc passes. In the experiment a high potential difference is applied across the sharpened metal tips. This results in vaporization of metal atoms which as a result undergo electronic excitation. This results in an arc discharge. The emission spectra is obtained and analyzed. Hartmanns constants were calculated using mercury lamp as the reference. The characteristic wavelengths were determined using this and the relative deviations in metal spectra.Hartmanns constants are:

OBSERVATIONS AND ANALYSISMERCURY SPECTRUMM

Profile for Hg spectrum

First peak Yellow light, Second peak Green light, Third peak Blue lightColorWavelength(nm)d(cm)

Yellow578.2.238

Green546.11.693

Blue4355.265

C = 927.61*10^-9B = 8.5* 10^-8 m^2 , A =.24 m

BRASS SPECTRUM

Profile of brass spectrum

Colord(pixel)d(cm)Wavelength(nm)

ellow1423.76507.65

Green1814.79480.24

Blue 12907.67396.36

Blue 23118.23396.36

Blue 33288.68360.94

IRON SPECTRUM

Colord(pixel)d(cm)Wavelength(nm)

Green 132.85558.04

Green 2691.82541.25

Blue 11985.24480.24

Blue 22065.45455.39

LASER BEAM AGAINST Hg SPECTRUM

The laser beam is in the red wavelength region as expected and in no other wavelength region. This verifies the monochromatic nature of LASER. The wave length of the laser is found to be 645 nm, which is close to the actual value of 650 nm.

RESULTThe spectral lines of iron and brass were photographed and the prominent emission wavelengths calculated using Hartmans constants.