Photometer, Principle, Beer-Lambert's Laws, Types, Applications, care and maintainance .pptx

A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Photometers measure: Illuminance, Irradiance, Light absorption
Scattering of light, Reflection of light, Fluorescence, Phosphorescence, Luminescence. Photometers are made in many forms for various applications. They may be used directly, as in photography or in measuring glare, colour variation, reflectance, or other qualities, or they may be incorporated into such devices as densitometers, spectrographs, and telescopes.

1. PHOTOMETRY The measurement of the intensity of brightness of light that can be perceived by the human eye is called photometry . Photometry is the science behind the measurement of light, which is  perceived in terms of brightness to the human eye.

2. PHOTOMETER A photometer is a device that measures the strength of electromagnetic radiation in the range of infrared radiation to ultraviolet radiation , including the visible part of the electromagnetic spectrum. Usually, a photometer converts light into electric current by using a photoresistor, photomultiplier, and photodiode.

3. Law’s of PHOTOMETRY Photometers examine how light interacts with reflective materials. The Photometers basically works on the principle of Beer-Lambert’s Law. Beer-Lambert Law  helps us define the relationship between the intensity of light and the exact quantity of substance present in the unknown solution.

4. Beer’s Law and Lambert’s Law where, A is the amount of light absorbed C is the concentration of the absorbing component A α c   Beer’s law was stated by August Beer which states that “When a monochromatic light passes through a solution the absorbance is directly proportional to the concentration of the components present in the solution”.

5. Lambert’s Law Johann Heinrich Lambert stated Lambert law. It states that “When a monochromatic light passes through a solution the absorbance is directly proportional to the path length of the solution”. A α b   where, A is the amount of light absorbed b is the path length or band width

6. Beer-Lambert’s Law Beer –Lambert’s law states that “When a monochromatic light passes through a solution the absorbance is directly proportional to the concentration and path length of the solution”. A α bc   where, A is the amount of light absorbed C is the concentration b is the path length or band width A = ε bc   where, A is the amount of light absorbed C is the concentration b is the path length or band width ε is molar absorptivity constant

7. Absorbance “ When a monochromatic light passes through a solution at a particular wavelength some amount of light is absorbed by the solution”, and the amount of light which is getting absorbed is called absorbance. Concentration of the sample is directly proportional to the Absorbance. But the Absorbance is negative logarithm of Transmittance. where, T is the transmittance A is Absorbance I is the transmitted light I is incident light

8. Transmittance “ when a monochromatic light passes through a solution at a particular wavelength some amount of light is absorbed by the solution and remaining light is getting transmitted”, and the amount of light which is getting transmitted is called Transmittance. Concentration of the sample is inversely proportional to the Transmittance. And the Transmittance is inversely proportional to Absorbance. where, T is the transmittance I is the transmitted light I is incident light

9. A = ε bc   where, A is the amount of light absorbed C is the concentration b is the path length or band width ε is molar absorptivity constant Molar Absorptivity Molar absorptivity, also known as the molar extinction coefficient, measures how well a chemical compound absorbs a given wavelength of light. It is an   intrinsic property   of the chemical compounds . The higher the molar absorptivity, the lower the concentration of compound. The  SI unit   of molar absorption coefficient is the square meter per  mole  (m 2 /mol)

10. Absorption Maxima It is a particular wavelength at which substance absorbs maximum light in the form of photons. The absorption maxima (λ max) is independent of concentration. The molar absorption coefficient is a measurement of how strongly a substance absorbs light. The larger its value, the greater the absorption.  It is used for quantitative estimation using Beer-Lambert’s Law.