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The word “photometry” is derived from two Greek words, “photos” and “-merry,” which both refer to the light measurement. The definition is that photometry is the science of measuring light. It is the science of determining light intensity. Quantitative light measurement is crucial in many domains of physics, astronomy, and industry.
A brief outline
Early photometry was done by inspecting objects directly with eyes that responded to changing intensities clearly. It helped people distinguish between different illuminating sources, but it didn’t tell them how much light they were emitting.
- Photometric Principles
Photometers study the interaction of light with reflecting materials. The photometers in the array represent the operating principle of photometry in several fields of research. The principle of photometry is used in some equipment to observe whether light absorbs and/or reflects wavelengths. Light is measured by turning it into an electric charge and detecting the intensity of the electric current created by the light in some equipment and systems. Photometers that beam white light at a surface to quantify the amount of light reflected at the instrument are also available.
When light passes through a coloured solution, particular wavelengths of light are selectively absorbed by the sample, resulting in a plot of the solution’s absorption spectrum. The wavelength of light at which maximal absorption occurs is referred to as the solution’s absorption maximum (max). The hue of the solution is determined by the wavelengths of light that are not absorbed by the solution and are instead transmitted through it.
Applications of Photometry
- The contrast ratios of cathode-ray tubes, flat panel screens, and liquid crystal displays are measured using highly sensitive photometers.
- Goniophotometers are used to assess the contrast and luminance of flat panel displays from a variety of perspectives.
- Photometers are used to test vehicle dashboards and cockpit panels quickly and accurately.
- Photometers are also used to measure the brightness of theatre screens, the transmittance of filters, the uniformity of projection systems, and the reflectance of paper, ceramics, and fabrics.
Significance of Hc Verma Solutions Class 11 Chapter 22 photometry in IIT JEE exam
The subject of photometry is given a 5% weighting. A spectrophotometer is one of the primary subjects covered on this exam. You will be asked 4 to 5 questions in this chapter.
What role does a photon play in photometry?
The photoelectric effect can be used to quantify the intensity of light using a photon, which is an elementary particle. When a photon absorbs and ejects an electron, it performs work.
What is photometry and why is it important?
Photometry is crucial in a variety of domains, including physics, astronomy, and technology. It aids in the identification of various light sources as well as the measurement of their intensities. Photometry has been used to calibrate light measurement devices.