Monday, November 28, 2011


1.            What is dispersion? How is it caused?
a)      The phenomenon of splitting or separation of composite light into its constituent colors is called dispersion.
b)      It is caused due to the difference in the frequency or wavelength of the constituent colors
2.            Mention the range of wavelength of visible spectrum?
                The wavelength of visible spectrum ranges from 400nm to 700nm.
3.            What is meant by a pure spectrum?
                A pure spectrum is a spectrum in which the constituent colours occupy their respective positions and are distinct.
4.            What is a spectroscope?
                A spectroscope is an instrument used to obtain pure spectrum of a composite light using a prism.
5.            Mention the different parts of a spectroscope?
                Collimator, telescope, prsim and prism table are the different parts of a spectroscope.
6.            List three uses of spectroscope?
                Spectroscope is used:
·         To study the elements present in the sun
·         To identify the elements present in the solar atmosphere
·         In spectrochemical analysis in industries, medicine and crime detection
7.            What is a continuous spectrum?
                A rainbow like spectrum obtained from sunlight, light from a filament of a lamp, molten iron or a candle is called a                 continuous emission spectrum.
8.            What is a line emission spectrum?
·         The spectrum formed when gases of vapors are made to emit light is called line emission spectrum.
·         It consists of a number of sharp, bright colored lines against a dark background.
·         These lines are the slit images of different colors.
9              What are Fraunhoffer lines?
·         When white light from a carbon lamp is passed through sodium vapor, then the continuous spectrum will have two dark lines in the yellow region.
·         Similarly the solar spectrum will have several dark lines in its spectrum.
·         These are called Fraunhoffer lines.
10.          Explain Raman Effect?
·         When a beam of monochromatic light was passed through an organic liquid such as benzene or toluene, the resulting scattered light was polychromatic and not monochromatic as the incident light.
·         The scattered light contained higher and lower frequencies in addition to the incident light.
·         This phenomenon is called Raman Effect.
11.          What is the important difference between Raman scattering and Rayleigh scattering?
                Rayleigh scattering is coherent scattering, while Raman scattering is incoherent scattering
12.          Mention one application of Raman Effect.
                Raman Effect is useful to understand the structure of molecules that constitute matter.
1.            What is a spectrum?
                The band of colours (wavelengths) obtained by dispersion of a narrow beam of composite light is called spectrum
2.            State Rayleigh’s principle on dispersion.
                According to the principle, the intensity of scattered light is inversely proportional to the fourth power of the                 wavelength.
3.            Name the scientist who predicted the theoretical background for it.
                Smekal predicted the theoretical background for Raman Effect.

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