THEORY: –
A spectrometer is use to measure the necessary angle. the spectrometer consists of three unit: 1) collimator, 2) telescope, and 3) prism table, its base and telescope can be independently moved around their common vertical axis. A circular angular scale enables one to red angular displacements (together with two Vernier’s located diametrically opposite to each other).
In the experiment, we need to produce a parallel beam of rays to be incident on the prism. This is done with the help of a collimator. The collimator has an adjustable rectangular slit at one end and a convex lens at the other end. When the illuminated slit is located at the focus of the lens, a parallel beam of rays emerges from the collimator. We can test this point, with the help of a telescope adjusted to receive parallel rays. We first prepare the telescope towards this purpose as follows:
The dispersive power of the material of a prism is given by
where , δ_{mB} and δ_{mR} are the angles of minimum deviation for Blue and Red colors respectively and A is the angle of the prism .
Therefore , Dispersive Power= D.P.=
WHERE,
µ_{B}= and, µ_{B}=
where , δ_{mB} and δ_{mR} are the angles of minimum deviation for Blue and Red colours respectively and A is the angle of the prism
Therefore , Dispersive Power=
Procedure:
Experimental Results:
1.Determination of Vernier constant of the spectroscope:
2.Table for Determination of minimum deviation angle;
Color of light | Vernier -1 | Vernier -2 | Mean δ_{m }(degree) | ||||||
MSR | VSR | TR | MSR | VSR | TR | ||||
Blue | |||||||||
Red | |||||||||
Direct Reading |
3.Table for Determination of angle of prism :
No. Of Vernier | Reading of telescope on left side(R_{1}) | Reading of telescope on right-side(R_{2}) | 2A=R1~R2
(degree) |
Mean 2A (degree) | A in
degree |
||||
MSR | VSR | TR | MSR | VSR | TR | ||||
1 | |||||||||
2 |
Result: