defr Glossar

Refractive index

The refractive index indicates the extent to which a light beam is deflected when passing from vacuum into a given substance.

The relation between the turbidity value and the solids concentration of a suspension is influenced perceptibly by the light-scattering properties of the solid particles. The quantity of scattered light does not only depend on the concentration, but also on the particle size and the ratio of the refractive indexes of the particles and the medium.

The more the particles differ from the medium (i.e. the more their refractive indexes differ), the more light will be scattered by the particles. If there is no difference at all, no light will be scattered. This can be illustrated experimentally, namely by suspending SiO2 in liquids of differing refractive index and then plotting the resulting scattered light intensities against the refractive indexes:

Scattered light intensity (relative unit) of SiO<sub>2
Fig. 39: Scattered light intensity (relative unit) of SiO2 in methanol/benzothiazole mixtures with differing refractive indexes

At the minimum of the curve, there is virtually no scattered light at all and the suspension no longer appears turbid. At this point, the medium and the suspended SiO2 have the same refractive index (1.47). This method can be used to determine the refractive index of suspended particles.

The following table lists the indexes for some common substances.

Substance Refractive Index
a-SiO2 1.45 .. 1.47
Methanol 1.329
Water 1.333
Quartz (natural SiO2) 1.55
c-SiO2 1.48
Ca3 (PO4)2 1.60 .. 1.66
CaCO3 1.5 .. 1.7
Bone Ash 1.60 .. 1.66
Formazine 1.85
Al2O3 1.76
CaSO4 1.57
Yeast 1.49 .. 1.53
Polystyrene latex 1.59
Paraffin oil 1.48
PbO, Pb3O4, PbO2 2.3 .. 2.7
TiO2 2.6 .. 2.9
ZnO 2.0

In actual practice the carrier medium is usually air (1.00) or water (1.33), and its refractive index is included in the calibration of the turbidimeter. The refractive index has a perceptible effect on the measurement only in cases where the substance being measured differs sharply from the calibration substance.

Index

Contact distribution partner

{{selectedCountry.Name}} {{country.Name}}

Please select your businessarea

{{ba.Name}}

Please select

{{area.Name}}

Please select your businessarea

{{ba.Name}}
{{selectedCountry.Name}} {{country.Name}}
{{vm.getBusinessAreaStringByVendor(vendor)}} {{area.Name}}
{{vm.getBusinessAreaStringByVendor(vendor)}}
Leonardo Pio
Responsible for the application: Water, Industrial Processes, Beverages & Food for the regions: AG, LU, NW, OW, VS, BS, BL, SO, BE, FR, NE, VD, GE and JU
Andreas Corradini
Responsible for the application: Water, Industrial Processes, Beverages & Food for the regions: TI, GR, UR, GL, SZ, ZG, ZH, SH, SG, TG, AR and AI Traffic & Environment: whole Switzerland
Ihr Businesspartner für Getränke & Lebensmittel:
Für Wasser, Industrielle Prozesse, Verkehr & Umwelt kontaktieren Sie unseren Hauptsitz.

Your distribution partner for beverages & food:
For water, industrial processes, traffic & environment please contact our headquarters

Ihr Businesspartner für Getränke & Lebensmittel:
Für Wasser, Industrielle Prozesse, Verkehr & Umwelt kontaktieren Sie unseren Hauptsitz.

Your distribution partner for beverages & food:
For water, industrial processes, traffic & environment please contact our headquarters

Contact headquarters

Ralf Isenberg
Sales Manager ScrubberGuard
Öffnungszeiten:
Montag–Freitag 08:00–12:00 und 13:30–17:00
Feiertage & Betriebsferien:
Seppitag: 19. März 2024, Ostern: 29. März – 01. April 2024, Auffahrt: 09. Mai 2024, Pfingstmontag: 20. Mai 2024, Fronleichnam: 30. Mai 2024, Bundesfeiertag: 01. August 2024, Maria Himmelfahrt: 15. August 2024, Allerheiligen: 01. November 2024, Maria Empfängnis: 08. Dezember 2024, Betriebsferien: 24. Dezember 2024 – 02. Januar 2025
Opening hours:
Monday–Friday 08:00am–12:00pm und 1:30pm–5:00pm
Public & company holidays:
St Joseph's Day: 19. March 2024, Easter: 29. March – 01. April 2024, Ascension Day: 09. May 2024, Whit Monday: 20. May 2024, Corpus Christi: 30. May 2024, Federal Holiday: 01. August 2024, Assumption Day: 15. August 2024, All Saints Day: 01. November 2024, Conception of Mary: 08. December 2024, Company holidays: 24. December 2024 – 02. January 2025