Polarimeter: measuring optical rotationध्रुवणमापी: प्रकाशिक घूर्णन का मापनPolarimeter: measuring optical rotation
Class 12 Chemistry · Chapter 6 · interactive diagram
Parts and what they mean
- Light source (प्रकाश स्रोत) — Ordinary light vibrates in all planes.
- Ordinary (unpolarised) light (साधारण (अध्रुवित) प्रकाश) — Vibrations in every direction perpendicular to the beam.
- Polariser (Nicol prism) (ध्रुवक (निकॉल प्रिज़्म)) — Passes vibrations in only one plane → plane polarised light. (William Nicol made the first such prism.)
- Plane polarised light (समतल ध्रुवित प्रकाश) — Vibrations in a single plane.
- Sample tube with solution (विलयन वाली नमूना नली) — An optically active compound in it rotates the plane of polarisation.
- Rotated plane (angle α) (घूमा हुआ तल (कोण α)) — The angle of rotation α is what the polarimeter measures.
- Analyser (rotatable Nicol prism) (विश्लेषक (घूमने वाला निकॉल प्रिज़्म)) — Turned until the light is brightest again; the turn needed = α.
- Observer (प्रेक्षक) — Looks towards the light source.
- Dextrorotatory: d or (+) (दक्षिण-ध्रुवण घूर्णक: d या (+)) — Rotates the plane to the right (clockwise); a + sign is put before the degree of rotation.
- Laevorotatory: l or (−) (वाम-ध्रुवण घूर्णक: l या (−)) — Rotates the plane to the left (anticlockwise); a − sign is used.
- Racemic mixture: zero rotation (रेसिमिक मिश्रण: शून्य घूर्णन) — Equal amounts of (+) and (−) enantiomers cancel each other: written dl or (±).
Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake