Polarimeter Experiment’s Aim

To find the specific rotation of sugar solution by using Laurent’s Half Shade Polarimeter.

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Formula:

The specific rotation of sugar solution is determined by the formula; S = θ / LC where ‘θ’ is the rotation produced in degree, L is the length of the tube in the decimeter (1 decimeter = 10 cm) and C is the concentration of the active substance in gm/cc in the solution.

contd...

If length of the solution (tube) is in cm then the formula will be; S = 10θ / LC also, C = mass of the substance (M) / volume (V). So, specific rotation = (10 X θ X V) / (L X M)

Unit:

The unit of specific rotation is degree/(decimeter) x (gm/cm^3 ).

we use Laurent’s half shade polarimeter to measure the angle of a plane-polarized light beam

we use a monochromatic extended light source (sodium lamp with its      D Line, wavelength    589 nm).

Also a convex lens to make this sodium light parallel for falling on the Nicol prism which is called polariser.

Q1. Can you observe the polarization in sound waves too?

Ans. No, they have longitudinal nature, made only by one component, no transverse components.

Q2. What do you mean by the plane of polarization?

Ans. An imaginary plane that is parallel to the electric vector components or vibrations is known as a plane of vibration. 

Q3. What is the use of Nicol Prism?

Ans. It acts as a polarizer (through which plane-polarized light we obtain) and an analyzer (to detect the plane-polarized light).

Q4. Which substances are called dextro-rotatory?

Ans. Those substances which rotate the plane of polarization in the clockwise direction when the observer faces the source of light. Known also as right-handed substances.

Q5. What are those factors on which specific rotation depends?

Ans. thickness of the substance concentration of the solution temperature wavelength of light used

To Read More About the Experiment, Viva Questions and Answers  Click Below

By Dr. Sushil Kumar