what is the use of spectrophotometer?
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to test reading glasses
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It probably requires a mass spec technique.  Infrared might work.  Your detection level will be the problem.
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In physics,spectrophotometry is the quantitative study of electromagnetic spectra. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared. Also, the term does not cover time-resolved spectroscopic techniques.\nSpectrophotometry involves the use of a spectrophotometer. A spectrophotometer is a photometer (a device for measuring light intensity) that can measure intensity as a function of the color, or more specifically, the wavelength of light. There are many kinds of spectrophotometers. Among the most important distinctions used to classify them are the wavelengths they work with, the measurement techniques they use, how they acquire a spectrum, and the sources of intensity variation they are designed to measure. Other important features of spectrophotometers include the spectral bandwidth and linear range.\n\nPerhaps the most common application of spectrophotometers is the measurement of light absorption, but they can be designed to measure diffuse or specular reflectance. Strictly, even the emission half of a luminescence instrument is a kind of spectrophotometer.\n\nThere are two major classes of spectrophotometers; single beam and double beam. A double beam spectrophotometer measures the ratio of the light intensity on two different light paths, and a single beam spectrophotometer measures the absolute light intensity. Although ratio measurements are easier, and generally stabler, single beam instruments have advantages; for instance, they can have a larger dynamic range.\n\nVisible-region spectrophotometers\n\nVisible region 400-700nm spectrophotometry is used extensively in colorimetry science. Ink manufacturers, printing companies, textiles vendors, and many more, need the data provided through colorimetry. They usually take readings every 10 nanometers along the visible region, and produce a spectral reflectance curve. These curves can be used to test a new batch of colorant to check if it makes a match to specifications. Traditional visual region spectrophotometers cannot detect if a colorant has fluorescence. This can make it impossible to manage color issues if one or more of the printing inks is fluorescent. Where a colorant contains fluorescence, a bi-spectral fluorescent spectrophotometer is used. There are two major setups for visual spectrum spectrophotometers, d/8 (spherical) and 0/45. The names are due to the geometry of the light source, observer and interior of the measurement chamber. Scientists use this machine to measure the amount of compounds in a sample. If the compound is more concentrated more light will be absorbed by the sample.\n\ncomponents: 1. The light source shines through the sample. 2. The sample absorbs light. 3. The detector detects how much light the sample has absorbed. 4. The detector then converts how much light the sample absorbed into a number.\n\n[edit] Spectroradiometers\nSpectrographic representation of the light output of an incandescent bulb (left) and a fluorescent lamp (right)\nSpectrographic representation of the light output of an incandescent bulb (left) and a fluorescent lamp (right)\n\nSpectroradiometers, which operate almost like the visible region spectrophotometers, are designed to measure the spectral density of illuminants in order to evaluate and categorize lighting for sales by the manufacturer, or for the customers to confirm the lamp they decided to purchase is within their specifications.\n[edit] UV and IR spectrophotometers\n\nThe most common spectrophotometers are used in the UV and visible regions of the spectrum, and some of these instruments also operate into the near-infrared region as well. Spectrophotometers designed for the main infrared region are quite different because of the technical requirements of measurement in that region. One major factor is the type of photosensors that are available for different spectral regions, but infrared measurement
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Lithimus paper is used to gage pH level.  An acid turns red lithimus paper blue and a base turns blue lithimus paper red.
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The manufacturer may be able to supply you with the spectral analysis for a particular light source.  For example flourescent bulbs use UV to cause phosphors to emit light and may absorb most or all the UV in the process.
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one way is chlorophyll fluorimetry,a method of studying light absorption by photosynthetic pigments in marine algae.\nthis sight might help good luck.
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Optical Spectrum Analyzer (OSA) is probably what you're looking for...nice for discovering chemical composition of light source and probably a zillion other different things.
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Raman spectroscopy is commonly used in chemistry, since vibrational information is very specific for the chemical bonds in molecules. It therefore provides a fingerprint by which the molecule can be identified. The fingerprint region of organic molecules is in the range 500-2000 cm-1. Another way that the technique is used is to study changes in chemical bonding, e.g. when a substrate is added to an enzyme.\n\nRaman gas analyzers have many practical applications, for instance they are used in medicine for real-time monitoring of anaesthetic and respiratory gas mixtures during surgery.\n\nIn solid state physics, spontaneous Raman spectroscopy is used to, among other things, characterize materials, measure temperature, and find the crystallographic orientation of a sample.\n\nAs with single molecules, a given solid material has characteristic phonon modes that can help an experimenter identify it. In addition, Raman spectroscopy can be used to observe other low frequency excitations of the solid, such as plasmons, magnons, and superconducting gap excitations.\n\nThe spontaneous Raman signal gives information on the population of a given phonon mode in the ratio between the Stokes (downshifted) intensity and anti-Stokes (upshifted) intensity.\n\nRaman scattering by a crystal gives information on the crystal orientation. The polarization of the Raman scattered light with respect to the crystal and the polarization of the laser light can be used to find the orientation of the crystal, if the crystal structure (specifically, its point group) is known.
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A radiometer does what you describe. \n\nhttp://store.sundancesolar.com/solrad.html\n\n\nDirections to build a simple radiometer:\n\nMake a radiometer to measure solar energy. Colour the paper side of a gum wrapper black and cut in four pieces. Stick the pieces to each side of a match stick with the shiny sides all facing the same way. Wrap a thread around a pencil and attach to the match stick. Suspend in the jar and place in a sunny location. The radiometer will turn as it absorbs energy.
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You can measure it in a number of ways depending on the protein.\n\n-- pH may vary directly with concentration\n-- optical rotation measurements may work for some\n-- adding a dye to the protein and reading on a colorimeter\n-- Another way would be to degrade or react the protein in solution and then to measure the byproducts of the degradation/reaction by something as simple as a titration
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A grating spectrometer has a series of parallel grooves that are spaced apart approximately equal to the wavelengths of impinging photons.  It acts to help sort the photons.
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forensic chemists conduct many different analyses including tests to determine purity of drugs, drug concentrations in bodily fluids such as blood and urine, analysis of accelerants used in arson, trace analysis (glass, paint components, fibers, hairs, etc.), analysis of unknown substances and so on.\n\nThese analyses can be used in conjunction with other evidence to either incriminate or exonerate suspects, determine severity of sentencing criminals and even to rule out foul play all together.
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Spectroscopy is the branch of science (Physics) concerned with production and analysis of spectra (analogous range of radiations in order of wavelength), produced by a spectrophotometer.\n\nIn emission spectroscopy, a sample is normally excited by thermal energy. Atoms in the sample absorb thermal energy causing outer orbital electrons to become excited from their ground state to higher orbital energy level. After a short lifetime (10{+-}{+6} to 10{+-}{+9}s), the excited electrons return to the ground state. Simultaneously, electromagnetic radiations (normally in the form of light in the UV-visible region) are emitted. The emitted radiations are analysed by means of spectrograph, which separates various wavelengths.\n\nIn Plasma Emission Spectroscopy, the exciting medium/ agent is plasma. The term `Plasma' in Physics means a very hot/ high temperature ionised gas, sometimes described as the fourth state of matter (the other three being solid, liquid and gas). In this method of sample analysis, a `Plasma Source' is the basic component. (Plasma Emission Spectroscopy is similar to Optical Emission Spectroscopy in principles but differs in mechanism. In OES, the sample excitation is done by electric arc or spark mechanism in the temperature range of 3000-5000 degrees Celcius. In PES, the temperature range is 7000-9000 {+o}C.\n\nThe sample solution or the analyte solution is supplied to the `Plasma Source' by a `Nebulizer' assembly. On reaching the high temperature (7000-9000 degrres Celsius) plasma, the solution attains this high temperature and all types of molecular bonds break down. Free atoms or ions (electrically charged atoms) are produced, which emit their characteristic spectra. A `Monochromator' assembly is in position after `Plasma Source' for isolation of the desired analyte line (or spectrum). The intensity of an analyte line is directly proportional to the concentration of that particular analyte (element being analysed) in the sample solution. The `detector & read-out' assembly gives us the concentration of the particular element in the sample. Modern instruments being computer controlled, the analysis is very fast and needs little operator skill. (Depending on the technique of production, plasma may be of three classes — viz., D.C. argon plasma, Microwave plasma and Inductively coupled plasma (ICP). The ICP is the most widely used due to mechanical simplicity and operational advantages.\n\nTherefore, plasma Emission Spectroscopy is the method of analysis of various elements in a sample, by passing the sample/ analyte solution through a plasma (high temperature ionised gas) source, thereby exciting the outer orbital electrons of the analyte with simultaneous emission of electromagnetic radiations (in the form of lights), which are analysed by means of a spectrograph, which separates various wavelengths of analytes in the sample.
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laboratory apparatus ang its function
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Just use the Grease spot photometer at night.
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It sounds like an enzymatic assay for phosphatases. I did that myself a long time ago.\nIf I remember correctly 405 should be the wavelength at which you are measuring the absorbance, unless you mean that the value was 0.405\n\nYou need to make a standard curve: measure the absorbance for different samples of p-nitrophenol of known concentration (you prepare them yourself) and then do the plot absorbance vs concentration. You find the equation for the curve by linear regression and then you can use it to find out the concentration of p-nitrophenol in your samples. Be sure to have alkaline solutions in order to have practically all of the p-nitrophenyl molecules in the p-nitophenoxy form as the anionic form is yellow and the protonated colorless.\n\nThe exact math depend on the specifics of your experimental set-up.\n\nAs for the second question it is not very clear what you mean.
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By the process called spectroscopy. It is the separation of light spectrum by different methods (a prism more often). Now, a type of atom, like helium for example, will absorb a small wave light in the light spectrum (this appearing to us like a thin, black, vertical line). Every atom type absorbs different light Wave. By knowing the spectrum of every single atom, we can superpose them and "see" who's`s who, only by having sun light