Wavelength and refractive index relationship test

Wavelength and the Index of Refraction

wavelength and refractive index relationship test

Calculate critical angle given refractive index. Angles of refraction can be calculated using known speeds or wavelengths. In the equation above, v_{1}. Refractive index is the ratio of the velocity of light of a specified wavelength in sines of the incident and refractive angles of light in the tested liquid is equal the relationship between the molecular weight of a solvent and its refractive index . The refractive index has linear relationship with the concentration of sugar solution. The diversity of methods is largely due to differences in applications, test.

BBC Bitesize - Higher Physics - Refraction of light - Revision 1

By measuring the refractive index of a binary solution, one can determine the composition of the solution [ 34 ]. So, measurements of refractive index are widely used in many industrial and research applications to determine the concentration of the solution [ 3 - 6 ]. There are numerous methods for measuring the refractive index of a liquid solution that are well documented in literatures [ 1 - 10 ].

The diversity of methods is largely due to differences in applications, test objects and the required measurement accuracy.

Refraction of light

A separate class of devices for measuring the refractive index of transparent liquids consists of systems designed for examining liquids in cuvettes made of glass, quartz or other transparent materials. During the last decade, numerous practical devices based on the principle described above using various cuvettes have been constructed for determining the refractive index [ 6 - 9 ].

The refractive index varies with concentration, temperature, pressure, and wavelength [ 2 - 71011 ]. Recent studies [ 2 - 4 ] provided the detailed study on the concentration mapping by the measurement of refractive index of liquids.

Temperature coefficient of refractive index can also be used to calculate thermal expansion coefficient [ 24 ]. Several techniques are reported in literature for the measurement of concentration and temperature dependence of refractive index of sugar solution using various techniques [ 2 - 7 ].

Various techniques have been developed to determine the contents of sugar in solutions [ 12 - 14 ]. The techniques are Inter digital Capacitor Sensor to determine the contents of sugar in solution [ 12 ]; optical Coherence Tomography to determine blood glucose concentration in diabetic patients [ 13 ]; Quantification of sugar in soft drinks and fruit juices by Density, refractometry, infrared spectroscopy and statistical methods [ 14 - 16 ] are some of the techniques so far developed.

The above mentioned techniques are industrial made instrument used to determine the concentration of sugar in solution. Such kind of instrument is very expensive and also not available in most laboratories. Materials and Methods Materials Locally constructed equilateral hollow prism, Red and Green Diode laser, He-Ne laser as light sources, digital electronic balance with a good accuracy for mass measurement were used.

In addition, different apparatus such as measuring cylinder to measure the volume of water, mercury thermometer to control the temperatures of the solutions and magnetic stirrer with hot plate for heating and mixing the solution. In addition, deionized water as solvent, locally produced sugar and soft drink beverages Pepsi, Coca, 7up, Sprite, Mirind and Fanta were used as our sample.

Calibration curve developed from the graph of refractive index versus the concentration of the solution. Numerical procedure of fitting the experimental data was carried out by linear curve fitting using origin 8 software. A theory and method for derivation of refractive index have been discussed elsewhere [ 1 - 25 ]. The angle of incidence is responsible for deviation produced in the path of light beam.

A monochromatic source of light Red, Green Diode laser and He-Ne laser was allowed to fall at angle of incident on the face of the liquid prism and the angle of minimum deviation was determined for each laser light. During the measurement the solutions were filtered before pouring into the hollow prism.

wavelength and refractive index relationship test

The hollow prism was also rinsed carefully after every measurement. The resulting negative refraction i. Ewald—Oseen extinction theorem At the atomic scale, an electromagnetic wave's phase velocity is slowed in a material because the electric field creates a disturbance in the charges of each atom primarily the electrons proportional to the electric susceptibility of the medium. Similarly, the magnetic field creates a disturbance proportional to the magnetic susceptibility.

wavelength and refractive index relationship test

As the electromagnetic fields oscillate in the wave, the charges in the material will be "shaken" back and forth at the same frequency. The light wave traveling in the medium is the macroscopic superposition sum of all such contributions in the material: This wave is typically a wave with the same frequency but shorter wavelength than the original, leading to a slowing of the wave's phase velocity.

Snell's Law & Index of Refraction Practice Problems - Physics

Most of the radiation from oscillating material charges will modify the incoming wave, changing its velocity. However, some net energy will be radiated in other directions or even at other frequencies see scattering. Depending on the relative phase of the original driving wave and the waves radiated by the charge motion, there are several possibilities: This is the normal refraction of transparent materials like glass or water, and corresponds to a refractive index which is real and greater than 1.

wavelength and refractive index relationship test

This is called "anomalous refraction", and is observed close to absorption lines typically in infrared spectrawith X-rays in ordinary materials, and with radio waves in Earth's ionosphere. It corresponds to a permittivity less than 1, which causes the refractive index to be also less than unity and the phase velocity of light greater than the speed of light in vacuum c note that the signal velocity is still less than c, as discussed above.

If the response is sufficiently strong and out-of-phase, the result is a negative value of permittivity and imaginary index of refraction, as observed in metals or plasma. This is light absorption in opaque materials and corresponds to an imaginary refractive index. If the electrons emit a light wave which is in phase with the light wave shaking them, it will amplify the light wave. This is rare, but occurs in lasers due to stimulated emission. It corresponds to an imaginary index of refraction, with the opposite sign to that of absorption.

Dispersion[ edit ] Light of different colors has slightly different refractive indices in water and therefore shows up at different positions in the rainbow. In a prism, dispersion causes different colors to refract at different angles, splitting white light into a rainbow of colors.

wavelength and refractive index relationship test

The variation of refractive index with wavelength for various glasses.