1. Definition and content
When light enters another transparent medium from one transparent medium, refraction occurs, which is caused by the different speeds of light in various media. Refractive index refers to the ratio of the speed of light in air to the speed in other substances. Measuring the refractive index of oil is to judge the purity of oil.
2. Measurement method
(1) Standard GB 55 27-20 10 Determination of Refractive Index of Vegetable Oils and Fats.
(2) Principle When light enters a prism with a refractive index of N from a substance with a refractive index of n, the angle of incidence is i, and the angle of refraction is 0, then:
sini/si action = Nin , n = Nsi action. The refractive index N of the prism is a known value, and the refractive index n of the measured substance can be .
(3) Take two drops of the mixed sample from the glass body for operation, drop it on the prism, turn the upper prism, and close the two mirrors tightly. After about 3 minutes, after the temperature of the sample is stable, turn the Amici prism handwheel and mirror. Turn the handwheel, so that the visual field is divided into two clearly visible light and dark parts, and the dividing line is just at the focal point of the cross, and record the reading of the scale and the temperature.
(4) Instrument Abbe refractometer (see Figure 2-3) and constant temperature Water Bath.
