16-01-2012, 03:27 PM
Physics Lab Viva Voce Questions and its answers Laser Parameters
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1. What is semi conductor diode laser?
Semiconductor diode laser is a specially fabricated pn junction diode. It emits laser light when it is
forward biased.
2. What is LASER?
The term LASER stands for Light Amplification by Stimulated Emission of Radiation. It is a device
which produces a powerful, monochromatic collimated beam of light in which the waves are coherent.
3. What are the characteristic of laser radiation?
Laser radiations have high intensity, high coherence, high monochoromation and high directionality
with less divergence.
AIR WEDGE
1.What is meant by interference of light?
When the two waves superimpose over each other, resultant intensity is modified. The modification in
the distribution of intensity in the region of superposition is called interference.
2.Is there is any energy loss in interference phenomenon?
No, there is only redistribution of energy ie, energy from dark places is shifted to bright places
3.What are interference fringes?
They are alternately bright and dark patches of light obtained in the region of superposition of two wave
trains of light.
SPECTROMETER GRATING
1.what is plane transmission diffraction grating?
A plane transmission diffraction grating is an optically plane parallel glass plate on which equidistant,
extremely close grooves are made by ruling with a diamond point.
2. In our experiment. What class of diffraction does occur and how?
Fraunhofer class of diffraction occurs. Since the spectrometer is focused for parallel rays, the source
and the image are effectively at infinite distances from the grating.
3. How are the commercial gratings are made?
A commercial gratings is made by pouring properly diluted cellulose acetate on the actual grating and
drying it to a thin strong film. The film is detached from the original grating and is mounted between
two glass plates. A commercial grating is called replica grating. In our experiment we use plane type
replica grating.
