Category: Physics Notes PPT

The aim is to explain nuclei’s masses and binding energies. The Liquid Drop Model is named after the fact that nuclei are thought to behave similarly to liquids (at least to first order). A liquid’s molecules are kept together by the Van der Waals force, which exists only between close neighbours.

 

Liquid Drop Model of the Nucleus

The liquid drop model of the nucleus explains forces in atomic nuclei as if they were created by a tiny liquid drop in nuclear physics. On a nuclear scale, however, the fluid is made up of nucleons (protons and neutrons). The liquid drop model accounts for the fact that the forces acting on nucleons on the surface vary from those acting on nucleons on the inside, where they are absolutely surrounded by attracting nucleons. This is analogous to considering surface tension as a factor in calculating the energy of a tiny liquid drop.

 

Key Facts of Nuclear Liquid Drop Model

1. Nuclei seem to have a constant density, according to scattering studies.

2. Nuclei have their own volume and surface, where various forces work.

3. The nucleus is spherical in its ground state.

4. This spherical nucleus can be twisted into a dumbbell shape and then broken into two fragments if enough kinetic or binding energy is applied.

5. For the binding energy of nuclei, the Weizsaecker formula is an empirically refined variant of the liquid drop model. The terms are as follows:

1. Volume term

2. Surface term

3. Asymmetry term

4. Pairing term

5.  Coulomb term.

6. Binding energies and masses of atomic nuclei can be calculated using the Weizsaecker formula. As a result, we can calculate the energy released per fission.

Semi-Empirical Formula

The von Weizsäcker mass formula (also known as the semi-empirical mass formula – SEMF) was published in 1935 by German physicist Carl Friedrich von Weizsäcker and was one of the first models that could accurately explain the action of nuclear binding energies and thus nuclear masses. The liquid drop model proposed by George Gamow is the basis for this theory.

The atomic nucleus, according to this model, behaves like the molecules in a drop of liquid. The fluid, on the other hand, is made up of nucleons (protons and neutrons) held together by a strong nuclear force. The nucleus’ liquid drop model takes into account the fact that nuclear forces on nucleons on the surface vary from those on nucleons in the nucleus’ interior. Other attracting nucleons completely surround the interior nucleons. The forces that shape a drop of liquid can be compared to this.

The nucleus is spherical in its ground state. This spherical nucleus can be distorted into a dumbbell shape and then broken into two fragments if enough kinetic or binding energy is applied. The splitting of such heavy nuclei must be followed by energy release since these fragments have a more stable configuration. This model does not account for all of the atomic nucleus’s properties, but it does account for the expected nuclear binding energies.

 

The Liquid Drop Model

George Gamow suggested the liquid drop model, which was further developed by Niels Bohr and John Archibald Wheeler. It treats the nucleus as an incompressible fluid drop with a very high density that is kept together by the nuclear force (a residual effect of the strong force), with a structure that resembles that of a spherical liquid drop. The liquid drop model, though crude, accounts for most nuclei’s spherical shape and allows a rough prediction of binding energy.

The mass formula is solely determined in terms of the number of protons and neutrons it includes. Five terms are described in the original Weizsäcker formula:

• Interior nucleon has a certain number of other nucleons in contact with it when an arrangement of nucleons of the same size is packed together into the smallest volume. As a result, the amount of nuclear energy emitted is proportional to the volume.

• The presumption that each nucleon interacts with the same number of other nucleons is corrected by surface energy. Since this definition is negative and proportional to the surface area, it is approximately equal to liquid surface tension.

• The potential energy of each pair of protons is known as Coulomb energy. The binding energy is diminished since this is a repulsive force.

• The Pauli exclusion theory is explained by asymmetry energy (also known as Pauli Energy). Uneven numbers of neutrons and protons mean that one form of the particle will fill higher energy levels while the other will leave lower energy levels empty.

• The propensity for proton and neutron pairs to form is explained by pairing energy. Due to spin coupling, an even number of particles is more stable than an odd number.

What are the major achievements of the liquid-drop model?

The liquid-drop model was an efficient model that helped scientists study atomic nuclei. The major achievements of the liquid-drop model are:

• It helps in predicting the atomic mass of the nuclei accurately.

• It helps in predicting the binding energies of various nuclei accurately.

• It helps scientists in predicting the emission of alpha particles and beta particles in radioactivity.

• It also efficiently explains the basic features of the process of fission.

What properties can be studied using a liquid-drop model?

The liquid-drop model can be efficiently used to study various properties of nuclear physics. This model considers the nucleus of an atom as a liquid. Nuclear properties, like binding energy, are studied through a liquid-drop model and are expressed in parameters that are associated with a liquid such as a volume energy, compressibility, and surface energy. The model was also used to explain how a nucleus performs when it undergoes fission.

What are the major advantages of the liquid-drop model?

The liquid-
drop model has various advantages in the field of nuclear physics. The major advantages of the liquid-drop model are:

•  The liquid-drop model explains the spherical shape and stability of nuclei very well.

• The model helps in predicting the binding energy of the nucleus and also helps us to know how much energy is available for consumption purposes.

• The model helps in explaining the radioactive phenomenon of artificial radioactivity and nuclear fission.

Some terminologies related to nuclear physics

• Nucleon: it refers to a proton or a neutron in the nucleus of an atom.

• Atomic number: it refers to the number of protons present in a nucleus and is denoted as Z.

• Atomic mass number: it refers to the number of nucleons present in a nucleus and is denoted as A =N+Z.

• Nuclide: it is the term given to a nucleus that contains a specific value of A and Z. the values of A and Z are written next to the chemical symbol in the form of subscript and superscript. The atomic mass number is written in the superscript and the atomic number is written in the subscript.

• Isotope: it refers to a nucleus that has the same atomic number but a different atomic mass number. The isotopes generally have similar chemical and atomic behavior but may possess different nuclear properties.

• Isotone: it refers to a nucleus that contains a different number of protons but the same number of neutrons.

• Isobar: these are just the opposite of isotopes and refer to a nucleus that has the same atomic mass number but a different atomic number.

• Mirror nuclei: these refer to a pair of unique nuclei wherein the number of protons in one nucleus, say A is equal to the number of neutrons in the other nuclei, say B, and the number of neutrons in A is equal to the number of protons in B.

Learn more about the liquid drop model of the atomic nucleus by from the top subject matter experts and build a strong foundation of nuclear physics. Find out deeper insights into this topic and proceed with better concepts to study advanced subjects.

Concept of Mach Number

For explaining the concept in a simple manner; Mach number 1 speed is equated to the speed of sound. If Mach 0.75 denoted, it would be considered 75% of the sound speed, which is also known as subsonic. If Mach 1.65 is indicated, it will be regarded as 65% faster than the sound speed, also known as supersonic speed.   

The sound depends on the surrounding space at a specific pressure and temperature; also, we can determine whether the flow is incompressible with the help of the Mach Number.

The surrounding space can either be gas or liquid. 

The boundary will be stable, but the medium can be flowing, or the boundary can travel in a medium, meaning it is at a rest state. There can be a situation where both the medium and boundary are traveling with some speed.

The medium can be channeled through various devices like the wind tunnels or sometimes may immerse in the medium. As the ratio of two speeds expresses the number, Mach Number is considered as a dimensionless number.

Since it was worked upon by an Austrian Physicists and Philosopher by Ernst Mach, it has been named as Mach number. Since it is a dimensionless quantity and not a measurable unit, the word Mach is put before the number, like Mach 1 and not 1 Mach.

What is Mach Number in Physics?

Mach Number Definition – The ratio of the flow velocity after a certain limit of the sound speed is known as the Mach number. In simple terms, it is the ratio of the speed of the body to the sound’s speed in the surrounding medium.

Mach Number Formula

The Mach Number formula is:

M = v/c

Where,

[M_{a}] = [frac{v}{c}]

[M_{a}] → Mach Number

V → speed or velocity of an object.

c → speed or velocity of sound.

In simple terms, the speed of sound can be equated to Mach 1. Thus Mach 0.75 will be 75% speed of the sound, also known as subsonic speed, and Mach 1.65 will be 65% faster than the speed of sound, known as the supersonic speed.

The local speed of sound is dependent on the pressure and temperature of the surrounding medium. Mach number can also determine if the flow is incompressible. The medium can either be gar or liquid. There are many scenarios where the medium can be flowing, but the boundary is stable, or the medium and boundary are both traveling, meaning that medium is at rest. Even though the boundary and medium both are traveling at a certain speed, but their velocities concerning each other are what matters. The medium can be channeled through various devices like the wind tunnel or can be immersed in the medium. Since Mach number is the ratio of two speeds, it termed as a dimensionless quantity.  

Mach Number Classification

Below based on the ratio values, the Mach number is termed in various regimes.

Subsonic:

The aerodynamic features like the rounded noses or the leading edges found in the commercial aircraft. They have a mach speed below 0.8.

Transonic:

The aircraft with swept wings built have a mach speed value of 0.8 – 2.1.

Supersonic:

The aircraft has a definite design and a complete movement of thin aerofoil sections, canards, and sharp edges that can fly at supersonic speed with mach speed value between 1.2 and 5.0.

Hypersonic:

The aircraft that fly at Mach value of between 5.0 – 10.0 has many distinctive features like the small wings and nickel-titanium skin that is cooled. A world record was created by the U.S. plane X-15, which flew at a speed of Mach 6.72.

High-Hypersonic:

When flying at mach levels of 10.0 – 25.0, thermal controls become an important factor while designing as the hotness of the surface needs to be considered beforehand.

Re-Entry Speeds:

When the mach speed is above 25.0, its craft doesn’t require wings but a blunt design.

Classification of Mech Regime

In particle Physics, a magnetic monopole is a speculative rudimentary molecule that is a separated magnet with just a single magnetic pole (a north pole without a south pole or the other way around). A magnetic monopole carries a net “magnetic charge”.

However, electric monopoles are a single-point charge, like an electron or positron, in which all the electric field lines point internally for a net negative electric charge or away for a net positive electric charge.

This is how a magnetic monopole and electric monopole looks like:

This page will give you ample information on magnetic monopoles, electric monopoles, Dirac monopole, and monopole uses.

Point to Note:

From the above text, we understand that all matter at any point disengaged to date, remembering each atom on the periodic table and each particle in the standard model, has zero magnetic monopole charge.

Consequently, the common phenomena of magnetism and magnets have nothing to do with magnetic monopoles.

Magnetic Monopole Discovery

Numerous early researchers credited the attraction of lodestones to two diverse “magnetic fluids” (“effluvia”), a north-pole fluid toward one side and a south-pole fluid at the other, which pulled in and repulsed each other in similarity to positive and negative electric charge.

However, an improved comprehension of electromagnetism in the nineteenth century showed that the magnetism of lodestones was appropriately clarified not by attractive monopole fluids, yet rather by a mix of electric currents, the electron magnetic moment, and the magnetic moments of different particles. 

Gauss’s law for magnetism, one of Maxwell’s equations, is the numerical explanation that magnetic monopoles don’t exist. 

In any case, Pierre Curie brought up in 1894 that magnetic monopoles could possibly exist, regardless of not having been seen up until this point.

What After Curie’s Statement on Magnetic Monopoles?

Pierre Curie called attention to in 1894 that magnetic monopoles could possibly exist, notwithstanding not having been seen up until now. 

Dirac Magnetic Monopole

The quantum theory of magnetic charge began on a paper by the physicist Paul Dirac in 1931.

In this paper, Dirac showed that assuming any magnetic monopoles exist in the universe, all-electric charges in the universe should be quantized (Dirac quantization condition).

The electric charge is, indeed, quantized, which is steady with (however doesn’t demonstrate) the presence of monopoles. 

What after the Dirac Monopole Experiment?

Dirac Monopole

Since Dirac’s paper, a few precise monopole experiments have been performed. 

Trials in 1975, and 1982 created concurrent occasions that were at first deciphered as monopoles, yet are currently viewed as inconclusive. Therefore, it stays an open inquiry whether monopoles exist. 

No Magnetic Monopoles

Further advances in hypothetical particle Physics, especially improvements in grand unified theories (GUTs), and quantum gravity, have prompted additional convincing contentions that monopolies do exist. 

Joseph Polchinski, a string-scholar, depicted the presence of monopoles as “probably the most secure bet that one can make about material science not yet seen”. These speculations are not really conflicting with the exploratory proof.

Why Theory on Magnetic Moments Still Remains a Confusion?

The theories mentioned in the “no magnetic monopoles” are not really conflicting with the exploratory proof. 

In some hypothetical models, magnetic monopoles are probably not going to be noticed, in light of the fact that they are too monstrous to even consider making in particle accelerators, and furthermore too uncommon in the Universe to enter a particle detector with much probability.

Dynamic Examination of a Magnetic Monopole

Some dense matter frameworks propose a design cursorily like a magnetic monopole, known as a flux tube. 

The finishes of a flux tube form a magnetic dipole, however since they move autonomously, they can be treated for some reasons as free magnetic monopole quasiparticles. 

Since 2009, various news reports from the famous media have mistakenly portrayed these frameworks as the long-anticipated revelation of the magnetic monopoles, yet the two marvels are simply cursorily identified with one another. These consolidated matter frameworks stay a space of dynamic examination/active research.

Now, Let Us Understand the Magnetic Monopole Uses:

Magnetic Monopole Uses

The reason is, by polarizing a spherical metallic chamber with an outward field (or by building dividers made of connected loops), the chamber gets loaded up with an etheric vacuum. This has demonstrated to be an exceptionally solid obstruction against outside attacks, particularly electromagnetic and etheric ones.

• Charged magnetic monopoles repulse each other actually like magnets. This could likely be utilized to construct a genuine magnetic levitation rail route, by setting sheets of comparative monopoles under the train and on the tracks. Propulsion would be possible by calculating the sheets, which would speed up or decelerate the train (however, making a monopole out of a sheet of metal has proven difficult, and impractical work).

Do You Know?

• Conceivable future headings of examination are: expanding the magnetization strength by building an all the more remarkable charging unit (potentially utilizing a few layers of curls masterminded in a progression of polyhedrons and momentum from homopolar generators or the Russian collapse method), constructing a twofold monopolar chamber and the quest for a magnetic tripole.

• A magnetic monopole is the magnetic rendition of a charged particle like an electron, and throughout the previous 70 years, physicists have accepted that one may exist someplace in the universe.

Introduction to Matter

Many of you have seen the change in the state of matter. For example, you must have seen the melting of ice cubes into the water. What is the change in phase here? The ice is converted into water that means it changes from a solid to a liquid state. Why does this happen? 

Here, we notice the change in states of matter. The boiling of water helps it to turn into vapour form. This is also a change in states of matter. In this article, we will know about many terms and formulas that are associated with the states of matter and their properties.

Properties of Matter

A substance changes its form (change in the state of that matter) when it gains a massive amount of energy. Due to energy absorption, the atoms and molecules start to move rapidly. The random movement of atoms and molecules results in the deformation of the molecular structure of the matter.

Types of Matter

When you read this article, the first thing you notice is about the three states of matter. How do you know the states? Well, here is the solution. 

When you notice a physical change in the matter, you can call it has changed its state. It transforms from one form to another. Change in the state of matter is reversible in many cases. However, chemical changes do not include reversible categories. 

The figure given below will show you the changing states of matter:

You must have heard of some common changes of state such as freezing, melting, deposition, sublimation, condensation, and vaporization. Well, these changes are the paths that lead to change in states of matter.

All of the changes satisfy one law, i.e., the Law of Conservation of Matter.  

Change Between the State of Solids and Liquids

Have you made some ice cubes by keeping them in a tray? If you have done this earlier, you can learn easily. But don’t worry. Here we provide you with a complete package of knowledge. 

When you put a tray full of water into a refrigerator, you will notice that they would have converted into ice after some time. This is called freezing. If you keep them on the same steel tray and supply heat, it will turn into the water once again.

Now let’s know why this behaviour is found among different matters, along with the examples of matter.

1. Freezing

When you keep the tray inside the freezer, the water comes into the interaction with the cold air inside the freezer. This helps the water to drop its temperature by keeping the molecules’ energy level to none. Water molecules do not have sufficient energy to collide with each other, and they turn into ice afterwards. 

The point at which a temperature is responsible for turning the water into ice is called the freezing point.

2. Melting Point

When put out of the freezer, it would have hardened. Now, if you apply the heat to initiate the change in the state of the molecules, they will start melting. This is because they absorb the heat energy provided via the tray.

The force of attraction between water molecules will exist no more when the temperature reaches a certain point. The point at which the entire ice cubes convert into water is known as the melting point.

Changes Between the State of Liquids and Gases

1. Vaporization

This is the phase where extreme heat supply helps the water to turn into vapour form. The force of attraction between molecules will fail at this stage.

2. Condensation 

When water vapour interacts with something, cooler surfaces, such as the plane of a mirror or any steel tray, some portion of the vapour will stay on its surface due to temperature difference. They stay in the form of water droplets. This is called condensation.

Changes Between the State of Gases and Solids

We know this phase as sublimation when the solid substances will pass directly to the vapour phase by skipping the liquid phase.

In this article, students will get to learn and fetch mechanical properties of solids class 11 notes. We are going to discuss the properties that solids have such as elastic behaviour of solids, stress and strain, stress-strain curve, Hooke’s law and elastic moduli.

What are the Mechanical Properties of Solids?

Mechanical properties of solids elaborates the characteristics such as the resistance to deformation and their strength. Strength is the ability of an object to withstand the applied stress, to what extent can it bear the stress. Resistance to deformation is how resistant any object is to the change of shape. If the resistance to deformation is less, the object can easily change its shape and vice versa.

Therefore, some of the mechanical properties of solids include:

1. Elasticity: When we stretch an object, it changes its shape and when we leave, it regains its shape. Or we can say it is the property to regain the original shape once the external force is removed. Example: Spring

2. Plasticity: When an object changes its shape and never comes back to its original shape even when external force is removed. It is the property of permanent deformation. Example: Plastic materials.

3. Ductility: When an object can be pulled in thin sheets, wires or plates, it has the ductile properties. It is the property of being drawn into thin wires/sheets/plates. Example: Gold or Silver

4. Strength: The ability to withstand applied stress without failure. Many categories of objects have higher strength than others.

There are various other properties but in this chapter of class 11 Physics mechanical properties of solids, we will mainly focus on the elasticity of solids. 

Stress and Different Types of Stress

It is the restoring force that develops on an object in the opposite direction; it is measured per unit area. For example, when a rubber ball is applied by an external force with our hands to compress it, at the same time the ball develops an opposite force that restrains it; however, both the forces are equal in magnitude. This restoring force developed by the object or ball is called stress.

Stress = Force/Area 

The S.I. unit of Stress is N/m square or Pascal (Pa)

Different Types of Stress are

1. Longitudinal Stress: Longitude means lengthwise; therefore, it can be defined as the restoring force per unit area when the force applied is normal to the cross-sectional area of the cylindrical body. There is change in the length of the object taking place. Example, when a cylindrical rubber object is tied with a heavy object, there will be longitudinal stress acting upon and the change in the length of the object takes place.

Longitudinal stress is divided into two sub-categories:

Tensile stress: In the above example, it can be said that tensile stress develops when force is applied to stretch the cylinder.

Compressive stress: When force is applied to compress the object.

2. Tangential or Shearing Stress

It is the restoring force per unit area when the force applied is parallel to the cross-sectional area of the body. There is a relative displacement occurring between the opposite faces of the body. 

3. Hydraulic Stress

It is the restoring force per unit area when the force is applied by a fluid like water on the body or object. Suppose, a ball made of rubber (which can be compressed) is dipped inside a river or sea, there is a force acting on the ball from all directions due to the pressure of the water. It results in the minor contraction of the ball. It is an example of hydraulic stress that you can include in the notes of mechanical properties of solids.

Strain and different Kinds of Strain

It is a measure of the deformation that can represent the displacement between particles in the body relative to a reference length. 

Strain is dimensionless quantity. If a rubber object is stretched from both the sides, the change in length represents the strain. 

Different Types of Strain are

1. Longitudinal Strain: It is the change in length to the original length of the body due to the applied longitudinal stress. It is a change in length divided by the original length.

2. Shearing Strain: It is the measure of the relative displacement of the opposite faces of the body due to the shearing stress. Shearing strain can be represented by tan Θ.

3. Volume Strain: It is the ratio of change in volume to the original volume as a result of the hydraulic stress. It is the change in volume divided by the initial or original volume. 

Hooke’s Law

It is named after the scientist Robert Hooke. Hooke’s Law states that stress developed is directly proportional to the strain produced in an object, within elastic limit (if the object is elastic material). An object that can come back to the original shape is its elasticity. Therefore, hooke’s law applies to elastic objects. It doesn’t apply to the plasticity property of solids. 

It can be, therefore, represented as Stress = k * Strain

Where k is the modulus of elasticity

Stress-Strain Curve

A curve drawn between stress and strain is called the stress-strain curve. When stress and stress are drawn along the y-axis and x-axis respectively, a linear graph is formed in the ideal situation of Hooke’s law. However, when actual experiments are drawn, a curve is formed  known as the stress-strain curve as shown below.

Solid is one of the four crucial conditions of issue (the others being fluid, gas, and plasma). The atoms in a strong are firmly pressed together and contain minimal measure of active energy. A strong is portrayed by primary inflexibility and protection from a power applied to the surface. Not at all like a fluid, a strong article doesn’t stream to assume the state of its holder, nor does it extend to fill the whole accessible volume like a gas. The particles in a strong are bound to one another, either in a customary mathematical cross-section (glasslike solids, which incorporate metals and standard ice), or unpredictably (an indistinct strong, for example, normal window glass). Solids can’t be compacted with little strain through gases can be compacted with little tension in light of the fact that the particles in a gas are inexactly pressed.

The part of physical science that arranges with solids is called strong state physical science and is the f
undamental part of dense matter physical science (which likewise incorporates fluids). Materials science is essentially worried about the physical and substance properties of solids. Strong state science is particularly worried about the combination of novel materials, just as the study of recognizable proof and substance arrangement.

Microscopic Description

The particles, atoms or particles that make up solids might be set up in a methodical rehashing design, or sporadically. Materials whose constituents are organised in a standard example are known as gems. Now and again, the customary request can proceed solidly over an enormous scope, for instance precious stones, where every jewel is a solitary gem. Strong items that are sufficiently huge to see and deal with are seldom made out of a solitary precious stone, however rather are made of countless single gems, known as crystallites, whose size can shift from a couple of nanometers to a few metres. Such materials are called polycrystalline. Practically all normal metals, and numerous ceramics, are polycrystalline.

In different materials, there is no long-range request in the place of the molecules. These solids are known as shapeless solids; models incorporate polystyrene and glass.

Regardless of whether a strong is glasslike or indistinct relies upon the material in question, and the conditions wherein it was shaped. Solids that are shaped by lethargic cooling will quite often be translucent, while solids that are frozen quickly are bound to be undefined. In like manner, the particular precious stone design embraced by a translucent strong relies upon the material in question and on how it was shaped.

While numerous normal items, for example, an ice solid shape or a coin, are artificially indistinguishable all through, numerous other normal materials include various substances stuffed together. For instance, an average stone is a total of a few unique minerals and mineraloids, with no particular substance piece. Wood is a characteristic natural material consisting essentially of cellulose filaments inserted in a network of natural lignin. In materials science, composites of beyond what one constituent material can be intended to have wanted properties.

Classes of Solids

The powers between the molecules in a strong can take an assortment of structures. For instance, a gem of sodium chloride (normal salt) is composed of ionic sodium and chlorine, which are held together by ionic bonds. In diamond or silicon, the iotas share electrons and structure covalent bonds. In metals, electrons are partaken in metallic bonding. Some solids, especially most natural mixtures, are held along with van der Waals powers coming about because of the polarisation of the electric charge cloud on every atom. The dissimilarities between the sorts of strong outcome from the contrasts between their holding.

Metals

The apex of New York’s Chrysler Building, the world’s tallest steel-upheld block building, is clad with treated steel.

Metals commonly are solid, thick, and great conduits of both power and hotness. The heft of the components in the intermittent table, those to one side of a corner to corner line attracted from boron to polonium, are metals. Combinations of at least two components in which the significant part is a metal are known as composites.

Individuals have been involving metals for an assortment of purposes since ancient occasions. The strength and dependability of metals has prompted their boundless use in development of structures and different designs, just as in many vehicles, numerous apparatuses and devices, pipes, street signs and railroad tracks. Iron and aluminium are the two most generally utilised primary metals. They are likewise the most bountiful metals in the Earth’s covering. Iron is most generally utilised as a combination, steel, which contains up to 2.1% carbon, making it a lot harder than unadulterated iron.

Since metals are great conveyors of power, they are important in electrical apparatuses and for conveying an electric flow over significant distances with little energy misfortune or dissemination. Accordingly, electrical power matrices depend on metal links to convey power. Home electrical frameworks, for instance, are set up with copper for its great leading properties and simple machinability. The high warm conductivity of most metals additionally makes them helpful for burner cooking tools.

The investigation of metallic components and their compounds makes up a critical piece of the fields of strong state science, physical science, materials science and designing.

Metallic solids are held together by a high thickness of shared, delocalized electrons, known as “metallic holding”. In a metal, particles promptly lose their peripheral (“valence”) electrons, shaping positive particles. The free electrons are spread over the whole string, which is held together solidly by electrostatic cooperations between the particles and the electron cloud. The enormous number of free electrons provides metals with their high upsides of electrical and warm conductivity. The free electrons additionally forestall transmission of noticeable light, making metals hazy, sparkly and glistening.

Further developed models of metal properties consider the impact of the positive particle centres on the delocalised electrons. As most metals have translucent design, those particles are generally organised into an occasional cross section. Numerically, the capability of the particle centres can be treated by different models, the least difficult being the almost free electron model.

Minerals

Minerals are normally happening solids framed through different land processes under high tensions. To be named a genuine mineral, a substance should have a precious stone construction with uniform actual properties all through. Minerals range in organisation from unadulterated components and basic salts to extremely complex silicates with a huge number of known structures. Interestingly, a stone example is an arbitrary total of minerals or potentially mineraloids, and has no particular substance organisation. By far most of the stones of the Earth’s covering comprise of quartz (glasslike SiO₂), feldspar, mica, chlorite, kaolin, calcite, epidote, olivine, augite, hornblende, magnetite, hematite, limonite and a couple of different minerals. A few minerals, similar to quartz, mica or feldspar are normal, while others have been found in a couple of areas around the world. The biggest gathering of minerals by a long shot is the silicates (most shakes are ≥95% silicates), which are made to a great extent out of silicon and oxygen, with the expansion of particles of aluminium, magnesium, iron, calcium and different metals.

Ceramics

Si3N4 clay bearing parts

Clay solids are made out of inorganic mixtures, normally oxides of substance components. They are synthetically inactive, and frequently are fit for enduring compound disintegration that happens in an acidic or scathing climate. Earthenware production for the most part can endure high temperatures going from 1000 to 1600 °C (1800 to 3000 °F). Special cases incorporate non-oxide inorganic materials, like nitrides, borides and carbides.

Conventional artistic unrefined substances incorporate earth minerals, for example, kaolinite, later materials incorporate aluminium oxide (alumina). The cutting edge ceramic materials, which are named progressed earthenware production, incorporate silicon carbide and tungsten carbide. Both are esteemed for their scraped area opposition, and henceforth observe use in such applications as the wear plates of deva
stating hardware in mining activities.

Most clay materials, like alumina and its mixtures, are framed from fine powders, yielding a fine grained polycrystalline microstructure that is loaded up with light-dispersing focuses similar to the frequency of noticeable light. In this manner, they are for the most part hazy materials, rather than straightforward materials. Ongoing nanoscale (for example sol-gel) innovation has, notwithstanding, made conceivable the creation of polycrystalline straightforward ceramics, for example, straightforward alumina and alumina compounds for such applications as high-power lasers. Progressed earthenware production is likewise utilised in the medication, electrical and hardware enterprises.

Earthenware designing is the science and innovation of making strong state artistic materials, parts and gadgets. This is done either by the activity of hotness, or, at lower temperatures, utilising precipitation responses from compound arrangements. The term incorporates the decontamination of natural substances, the review and creation of the synthetic mixtures concerned, their development into parts, and the investigation of their design, synthesis and properties.

Precisely talking, clay materials are fragile, hard, solid in pressure and feeble in shearing and strain. Weak materials might display critical elasticity by supporting a static burden. Durability demonstrates how much energy a material can ingest before mechanical disappointment, while break strength (signified KIc ) depicts the capacity of a material with inborn microstructural defects to oppose crack by means of break development and proliferation. Assuming a material has an enormous worth of break strength, the essential standards of crack mechanics propose that it will probably go through malleable crack. Weak break is exceptionally normal for generally artistic and glass-ceramic materials that regularly display low (and conflicting) upsides of KIc.

For an illustration of uses of ceramics, the outrageous hardness of zirconia is used in the production of blade sharp edges, just as other modern cutting devices. Ceramics, for example, alumina, boron carbide and silicon carbide have been utilised in tactical armour carriers to repulse enormous type rifle shoot. Silicon nitride parts are utilised in clay metal rollers, where their high hardness makes them wear safe. As a general rule, earthenware production is synthetically safe and can be utilised in wet conditions where steel orientation would be helpless to oxidation (or rust).

As one more illustration of artistic applications, in the mid 1980s, Toyota investigated the creation of an adiabatic clay motor with a working temperature north of 6000 °F (3300 °C). Artistic motors don’t need a cooling framework and subsequently permit a significant weight decrease and along these lines more prominent eco-friendliness. In a regular metallic motor, a large part of the energy let out of the fuel should be dispersed as waste hotness to forestall an emergency of the metallic parts. Work is additionally being done in creating artistic parts for gas turbine motors. Turbine motors made with ceramics could work all the more productively, giving aeroplanes more prominent reach and payload for a limited measure of fuel. Such motors are not underway, notwithstanding, in light of the fact that the assembling of clay parts in the adequate accuracy and toughness is troublesome and expensive. Handling strategies regularly bring about a wide conveyance of minute blemishes that often assume an inconvenient part in the sintering system, bringing about the multiplication of breaks, and extreme mechanical disappointment.

When a light source illuminates a perfectly diffused surface, it usually appears bright in all directions. Meanwhile, a polished surface will tend to appear illuminated only in one direction for a given position of an observer. 

So, the phenomenon due to which illumination takes place on a diffused or polished surface is known as a regular reflection of light. Moreover, the surface on which the reflection of light takes place is known as a mirror. 

Mirror Definition in Physics

In physics, a mirror is defined as a surface that reflects nearly all kinds of light incidents on it. Moreover, a mirror will keep on reflecting light in a regular fashion until or unless an opaque object is introduced between the reflecting surface and the source of light. 

Working of Mirrors 

When light hits a mirror surface, it reflects every colour of the spectrum. As a matter of fact, mirrors work on the principle of reflection. 

We know that the light either gets reflected or absorbed. In the case of a mirror, light is always reflected. The reason why the light gets reflected when it falls on a mirror is that at the microscopic level, it is a smooth surface.

In the case of a rough surface, it is reflected back in all directions and this is known as diffuse reflection but for smooth surfaces, it gets reflected in one single direction and is known as specular reflection. So, in the case of a mirror, it is a specular reflection. 

Terms Related to Mirrors 

• Incident Ray: The ray of light that hits the surface. 

• Reflected Ray: The ray of light that gets reflected after getting hit on the surface. 

• Normal Ray: The ray of light that is perpendicular to the reflecting surface.

• Refracted Ray: When the incident ray passes through a second medium, it is known as a refracted ray.

Types of Mirrors

There are different types of mirrors in physics. Mirrors can be broadly classified as plane mirrors, rotating mirrors, inclined mirrors, and spherical mirrors. Moreover, spherical mirrors can be further classified into two types, i.e. a concave spherical mirror and a convex spherical mirror.

Furthermore, this classification is explained with an illustration given below.

Before we carry on with our topic on Mirrors, brush up your memory on these essential pointers in the Q&A section discussed below.

Test Your Knowledge

1. What do you mean by a mirror image?

Ans: When light is incident on any type of mirror from a particular source, it is not only reflected, but it also creates a virtual image inside the reflecting surface. This virtual image, thus formed, is known as a mirror image. The features of a mirror image depend primarily on the type of mirror used. 

2. What is an incident ray and a reflected ray? 

Ans: A light ray, which travels from a source to a reflecting surface, is known as an incident ray. 

On the other hand, a ray of light which travels from a mirror to the image, formed due to reflection, is known as a reflected ray.

3. How do mirrors reflect light?

Ans. In the case of an ordinary house mirror, when a ray of light falls on its surface, the silver molecules behind the glass get excited by absorbing the photons. This makes the atoms unstable, so they tend to become stable again by reflecting those photons in the opposite direction. 

As you get to know about how many types of mirrors are there in optics, you should now also understand the detailed explanation on the important types individually. 

Plane Mirror

For example, let us consider a ray of light is incident on a plane mirror at a point. Regular reflection takes place, and an image is formed at point B. 

Now, the angle between this incident ray and the normal is the angle of incidence. Consequently, the angle between the normal and the incident ray is known as the angle of reflection. 

As per the Laws of Reflection of light, we can conclude that –

• The incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane. 

• The angle of incidence is the same as that of the angle of reflection

Example:

Any regular reflecting material which has a polished surface and is not curved in nature is an example of a plane mirror, like household mirrors, looking glass, etc.

Spherical Mirror

A spherical mirror can be defined as a portion of a hollow sphere whose one side comprises a reflecting surface whereas the other side has been silvered. 

As discussed earlier, there are two types of such mirrors which are –

A concave mirror is a type of spherical mirror which has a reflecting surface that is located inwards at the centre of the sphere. A concave mirror is that whose outer walls have been silvered and the inner surface is used for reflection.

In the case of a convex mirror, this reflecting surface is situated away from the center of the sphere. A convex mirror is that whose inner walls have been silvered while the outer surface is used for reflection.