How Does Atomic Absorption Spectroscopy Work?

Atomic Absorption Spectroscopy(AAS) is a quantitative analytical elemental technique that provides the total metal content of the sample and is almost independent of the molecular form of metal in the liquid sample. It analyzes the concentration of elements in a liquid sample based on energy absorbed from certain wavelengths of light. Alan Walsh, a Lancashire-born physicist was the one who worked on determining the small concentrations of metallic elements using spectroscopy. He got this idea in the 1950s while working in his garden. He worked on it for several years and finally convinced the manufacturers to use AAS for metallic determination. The first commercial AAS was launched in the 1960s and since then this technique has established a robust place in the field of analytical techniques.  Principle of Atomic Absorption Spectroscopy The AAS technique is based on the absorption of energy by ground-state atoms in the gaseous state. It states […]

Comparison Microscope: Principle, Features & Applications

The invention of the microscope has been a boon in the scientific field which allowed scientists to visualize things or matter or objects which are not visible to the naked eye. The first microscope came into existence with the invention of early microscope, by a Dutch spectacle maker Zacharias Janssen in 16th century. With the passage of time and different needs for visualization, various kinds of microscopes were invented and one of them was the comparison microscope.  The comparison microscope was invented for side-by-side analysis of objects. As the name suggests, it compares two objects simultaneously. It is an instrument that combines two light microscopes side-by-side connected via an optical bridge which facilitates a split view window. It is one of the important instruments used in forensics. Development of Comparison Microscope The comparison microscope was first launched as a prototype in Germany in 1913. However, it was not popularised in […]

Scanning Electron Microscope

Scanning Electron Microscope (SEM) is a type of electron microscope that produces a three-dimensional image of a microscopic object. As the name suggests the microscope forms the images by scanning the surface of the object with the help of a focused beam of electrons. SEM was first developed in 1937 with the contribution of Manfred von Ardenne. However, the first commercial instrument was launched in 1965.  SEM image reveals information like the morphology, crystalline structure, chemical composition, and orientation of materials/components of the sample. SEM requires electrons that have low kinetic energy because the interaction only with the surface up to a few nanometers of depth is required rather than penetrating deep inside the sample. Principle of Scanning Electron Microscope SEM works on the principle that, “When the accelerated electrons with specific amounts of kinetic energy interact with the surface of the sample, the energy is dissipated in the form […]

Types of Microscopes

There are a lot of things, both living and non-living, on this earth and not everything is visible to the naked eye. Therefore, an instrument called a ‘microscope’ was developed to enter the world of those tiny things.  The word ‘microscope’ is derived from the Greek words ‘mikros’ which means “small” and ‘skopein’ which means “to examine or look“. The first microscope developed was a simple microscope in 1590. It has been said that the first compound microscope was developed in 1620 in Europe but the founder is unknown. Galileo Galilei discovered in 1610 that a telescope can also focus on small objects. He worked on it and his work was appreciated by Giovanni Faber, who named Galilei’s instrument a microscope in 1625.  Since the variety of microscopic organisms or things is vast and they cannot be viewed by a single microscope. Therefore with the difference in the need for […]

Soil As A Forensic Evidence In An Investigation

Soil is a biogeochemical material found on the outermost layer of earth’s crust. It is composed of various layers where the distribution of constituents is not uniform. The heterogeneous nature of the soil is due to the variation in weathering, climatic and anthropogenic factors which vary with respect to distance. That’s why it is concluded that the soil of a specific area is individual to that area in respect of its chemical, physical and biological characteristics (Law of Individuality). Trace evidence is one of the important piece of evidence present at a crime scene under the radar of a crime scene investigator since they are difficult to erase and easy to solve a case if analyzed properly. They are admissible in court as an evidence and soil is one of them. Though soil is not connected directly to any human yet they still help in examination of crime scene and […]

A Detailed Note on Electrocution

Death or severe injury caused by electric shock passing through the body is known as Electrocution. Electric burns are a kind of thermal injury. The tissue damage associated with an electric injury occurs when electric energy is converted to thermal energy or heat. Accidental death due to electric currents was not reported until 1879. The direct current is comparatively less dangerous than the alternative current. The AC between 40 to 150 cps is most dangerous. A current of 50- 80 mA of AC can be fatal within seconds whereas 250 mA DC is non-fatal. The cause of death in electrocution is ventricular fibrillation, tetanic asphyxia, respiratory arrest, cardiac arrest, cerebral anoxia, burns, secondary injuries sustained. When high voltage current is passed through the body, death happens due to arching of electric current or due to ignition of clothes. When electric current passes through the body it can cause injuries like […]

Chemical and Instrumental Methods of Soil Analysis

Soil is the uppermost layer of the earth’s crust, consisting of many organic and inorganic materials, including microorganisms. The soil composition differs from place to place. The soil of the same area at a distance of 100-200 meters differs in its composition. This feature of individuality makes soil a piece of critical evidence. In the upcoming sections, we will describe different chemical and instrumental methods of soil analysis. Soil as evidence has high evidential value because of its high evidential value. Identifying extreme complexities in minerals, oxides, organic matter, microorganisms, etc., along with its physical features of size and density, can link a person to the crime scene. The techniques of soil analysis, such as wet sieving, dry sieving, screening, polarizing microscope, etc., help us to identify them. Along with studying the methods of soil analysis, we will also look at the history of soil as evidence to know the […]

Dissecting/Stereo Microscope | Principle, Parts, Working, and Applications of Stereo Microscope

Microscopes are used widely nowadays for researches as well as academic experiments in schools and colleges. While Simple microscope and Compound microscope are used commonly for studies but stereo microscope is no less. There are a lot of microscopes in the market right now and stereo microscope like others is different and beneficial in its way to the scientists. It is known for low magnification but serves many different and important purposes. Stereo microscope also known as Dissecting microscope is an optical instrument used for the observation of objects in low magnification, in which the instrument uses the light reflected from the surface rather than using the transmitted light from the object. It helps in examining the objects in 3D such as rocks, fibers, soil, electronic items, etc. The 3D examination of objects by Stereo microscope makes it unique than other microscopes. Here, in this article we will talk about […]

Simple Microscope vs Compound Microscope

Simple microscope and Compound microscope are the two different microscopes having different properties in terms of use. So in this article, we will discuss Simple microscope vs Compound microscope. Microscopes are the instruments used to magnify the images of a small object. There are many different kinds of microscopes with different uses and properties used for different purposes. Microscopes are used in laboratories and academic experiments. To use microscopes we must know about them. A simple microscope is an instrument that uses a single optical lens for the magnification of an object. A compound microscope is an instrument that uses two lenses for magnification of images which include one objective lens and an eyepiece. A simple microscope includes a hand lens, reading glasses, etc. while a compound microscope is a laboratory instrument. Here, we will learn how Simple microscope differs from Compound microscope in their properties and applications. Simple microscope […]

What is a Compound Microscope? Applications of Compound Microscope

Microscopes are useful in all fields of science for a deep study of any specimen and a Compound microscope is one of the kind. It has proven useful to pharmaceutical companies, fiber industries, Biological study and Forensic investigations as well. There are many different microscopes invented but the compound microscope is quite different and beneficial to scientists. It helps in obtaining high magnification of the samples up to 1000x as compared to a Simple microscope (100x magnification). The compound microscope is one of the kind invented by Dutch lens maker Hans and his son Zacharias Janssen. It is a high magnifying microscope also known as a high power microscope or biological microscope that helps in the examination of minute specimens at high magnification which are not visible to the naked eye such as bacteria or virus. Compound microscope has many properties that has made it superior over other microscopes. Here, […]

What is a Simple Microscope? Applications of Simple Microscope

Microscope is a laboratory instrument that is used to see an enlarged image of a small object which reveals the microscopic properties of that object which are not possible to see with a naked eye. The most common type of microscope is the Optical microscope also known as the Light microscope which uses the light focused through the lenses on the object to form an enlarged image. An optical microscope can be classified into two i.e., Simple microscope and Compound microscope. Other types of microscopes used are Polarized microscope, Electron microscopes, Fluorescence microscope, Stereo-microscope, etc. What is a Simple microscope? A simple microscope is similar to a magnifying glass that uses a double convex lenses to form an erect and enlarged image of an object when placed within its focal length. The image formed is virtual which means that the formed image cannot be projected on a screen. The first […]