Ordinary Dry Cell

Introduction to ordinary dry cell:

The best known voltaic cell for commercial use is the ordinary dry cell. The dry cell which we use in torches, transistor radios, toys and laboratory experiments, was invented by Lechlanche in 1868. The dry cell converts chemical energy into electric energy. A single dry cell gives a voltage of 1.5 volts.


Construction of ordinary dry cell


A dry cell consists of a carbon rod placed at the centre of a zinc container. The space between the carbon rod and the zinc container is filled with a moist paste of ammonium chloride (NH4Cl) and zinc chloride (ZnCl2) mixed with manganese dioxide and powdered carbon. In dry cell, the carbon rod acts as a positive electrode (cathode); the zinc container act as a negative electrode (anode); and the ammonium chloride and zinc chloride acts as electrolyte. Manganese dioxide removes the hydrogen gas formed during the working of dry cell (by oxidising it), and prevent it settling on the positive electrode of the cell (so that it may not interfere with the working of the cell).


How ordinary dry cell works:


Actually, manganese dioxide works as depolariser (depolariser is a chemical which removes hydrogen and prevent it settling on the positive elctrode of the cell). powdered Carbon present in the dry cell helps in the movement of charges between the electrodes in the cell and hence reduces the internal resistance of the cell. Please note that a dry cell is not completely dry. The presence of little water in the miost paste is essential for the movement of ions.The dry cell is sealed at the top with the sealing wax to prevent evaporation of moisture and the carbon rod has a brass cap for better electrical contact. The zinc container has an outer insulation of card board case. The card board case, however does not cover the bottom of the cell. In dry cell , the zinc container is the producer of electrons for the usable current.

Geothermal Resources

Introduction to geothermal resources:

Geothermal energy is the heat from inside the earth, a kind of domestic energy which is reliable, cost effective and environmentally friendlier than other conventional sources of energy. It is released at an average heat flux of 60 mW/m2 by conduction. It is used for direct-heat use and electrical power generation.

Through production wells hot water is pumped up from the underground reservoir for generation of electricity, and then converted to steam by discharge of pressure. The steam is led into a turbine engine, which turns a generator. Remaining geothermal fluid is goes back into the reservoir to maintain its pressure.


Resources for geothermal energy


The global tectonic plates dictate the location of geothermal resources. Geo-dynamic processes like subsidence, sub-duction, uplift, fracturing result in geothermal features like volcanism and hydrothermal convection.

Common geothermal resources are:

A deep simple hot rock or magma body.

Heat carrying fluid.

Fractured or spongy rock.

Top rocks provide an insulating cover

The general geothermal resources need a fluid for heat transfer.

For direct-heat application, heat is extracted from the geothermal water at temperatures less than 120 o C which is used for greenhouse, home heating, vegetable drying and other small scale industries. The hot water spent, is used for direct application.


Technology and Resource Type


Geothermal resources  can be just liquid water, dry, a mixture of steam and water or mainly steam and varies in temperature from 30-350 o C. Water is the medium to transfer geothermal heat from the earth which is naturally occurring in most places but modern technologies extract this energy from hot dry rock resources. The temperature of the resource indicates the type of technologies required or its uses.


Conclusion to geothermal resources


Geothermal electric plants are built on the edges of tectonic plates as high temperature geothermal resources are available close to the surface

There are approximately 8,000 MW of generating and 12,000 MW of direct use geothermal resources world-wide.

Iintroduction to Nuclear Physics

Introduction to nuclear physics:

Matter, right from a tiny speck of dust to a gigantic cosmic entity consists  of atoms. An atom consists of a central part called nucleus around which electrons will revolve. Another question comes to our mind is that whether a nucleus too have a structure like an atom? If so, what is the nature of its constituents and how are they held together in the nucleus? In unfolding such series of questions, a separate branch in physics called  Nuclear physics has evolved.Having problem with Linear Speed Formula keep reading my upcoming posts, i will try to help you.


Introduction to Nuclear Physics by Henri Becquerel


The year 1896, marks the beginning of nuclear physics. It is in this year, the French physicist Henri Becquerel discovered the phenomenon of radioactivity in one of he Uranium compounds, quite accidentally. The phenomenon of radioactivity refers to a particular type of invisible radiation emerging from certain specific substances. At first sight, this radiation was quite puzzling for scientists. Later on the experiments conducted by Ernst Rutherford and others proved that this radiation consists of alpha, beta and gamma rays. This rays were found to be originating in the  nucleus. The experiments conducted by Geiger and Ernst  Marsden, at the suggestion of Rutherford in 1911, involving the scattering of alpha particles have revealed that there exists a positively charged nucleus at the centre of each atom. It was James Chadwick's discovery of neutron in 1932 that clinched the issue of nuclear structure.


Conclusion on Introduction to Nuclear Physics


After the discovery of neutron Werner Heisenberg proposed that the nucleus consists of neutrons and protons. The discovery of artificial radioactivity in 1933 and nuclear fission in 1938, development of first controlled fission reactor in 1942 are some of the important milestones in the field of nuclear physics.

More recently, the scientists are focusing on the nature of nuclear forces and are trying to integrate electro weak force ( which resulted after integrating electromagnetic force and weak nuclear force) ,  strong nuclear force and gravitational force.

Subtracting Vectors Physics

Introduction to Subtracting Vectors Physics

Man's curiosity to know 'nature ' always drives him to evolve new concepts, and identify new relationships among physical quantities. The relationship among the quantities may be of algebraic or geometric in nature. It is cumbersome to represent the relationships geometrically in three dimensions. The concept of vectors and scalars solves this issue. Equations in vector form indicate both mathematical and geometrical relationships among the quantities. Physical laws in vector form and very compact, and independent of choice of coordinate system.I like to share this Displacement Vector with you all through my article.


Subtracting Vectors in Physics : Definition of Vectors


A vector is characterised by an absolute value(magnitude) and a direction. The vector, as a mathematical object, is defined as a directed line segment. Displacement, velocity acceleration, force momentum, angular momentum are a few examples of vector quantities.

A vector is geometrically represented by an arrow. Length of the arrow is proportional to the magnitude of the vector; head of the arrow gives the sense of direction. A displacement vector is represented as an arrow. The initial point( or tail ) of the vector is A, the final point (or head) is B. The length AB ( measured to a scale ) is the magnitude of the vector. The direction of the vector is specified by the angle (in counter clock - wise direction) the arrow makes with a reference line. The magnitude of the displacement is 30m. Its direction is 300 north of east.  In print a vector is represented by a single bold type letter such as d .


Subtraction of Vectors in Physics


Before the operation of subtraction is taken up it is convenient of define negative of a vector.  Negative of a vector is another vector having same magnitude but opposite direction. When a vector and its negative vector are added the resultant is Zero .

i.e.,  a + (-a) = 0. It is said that -a is anti parallel to a.

The concept of negative vector enables one to carry out subtraction of vectors. If vector b is subtracted from vectors a then add -b ( negative of vector b) to a.

a + (-b)  =  a - b

Uranium Nuclear Fuel

Introduction to Uranium nuclear fuel:

The basic fuel materials for the generation of nuclear power are the elements Uranium and Thorium. Of these, Uranium has played a major rule. Uranium is by no means a rare substance and it has been estimated to be around 4ppm of the earth’s crust. In fact, Uranium is more abundant  than relatively familiar elements such us silver, mercury, bismuth and cadmium. Although the estimated total weight of Uranium in the earth’s crust is 1014 metric tons yet most deposits are of such a low grade that the extraction of the metal would appear to be uneconomical. Uranium is extracted from the ores containing primary minerals Pitchblende and Uraninite (UO2  and  U3O8). Uranium is solvent extracted to finally produce ‘yellow cake’ containing 75% to 85% of  U3O8.  This is subjected to further treatment leading to almost pure Hexafluoride (UF6) as a product.  Uranium dioxide (UO2), Uranium metal, Uranium carbide and Uranium nitride are some of the final products that will be used as reactor fuel.Please express your views of this topic Definition of Torque by commenting on blog.

Uranium metal fuel:


Metallic Uranium was used as a fuel in most of the earlier nuclear reactors, largely because it provides the maximum number of Uranium atoms per unit volume. Since it has poor mechanical properties and great susceptibility to radiation damage, Uranium metal fuel  is not used in power reactors in many countries. It was used as a fuel in the older gas-cooled reactors.


Uranium dioxide nuclear fuel:


Uranium dioxide (UO2) , a ceramic which is the most common fuel material in commercial power reactors, has the advantages of high-temperature, stability and adequate resistance to radiation. It also has a high melting point of 2865oC and is chemically inert to attack by hot water. It is this property which makes it attractive for use in water- cooled reactors, where the consequences of a cladding failure could be catastrophic if the fuel material reacted readily with the water at the existing high temperature. Another beneficial property of Uranium dioxide is its ability to retain a large proportion of the fission gases provided the temperature does not exceed about 1000oC. The major disadvantage of Uranium dioxide as a fuel material is its low thermal conductivity, although this is partially offset by the fact that very high temperatures are permissible in the centre of the fuel element.

Solar Wind Geothermal

Introduction to solar, wind and geothermal energy:

Renewable energy comes from natural resources like sunlight, tides, wind, rain and geothermal heat. Three major renewable energy resources are wind power, solar energy and geothermal energy. Advantage of renewable energy is that they are inexhaustible, environmentally friendly with low dangerous pollutant emissions.



Solar energy


Solar energy is derived from the sun in the form of solar radiation. Electrical generation by solar power relies on heat engines and photovoltaic. Solar applications include day lighting, solar architecture, solar cooking, solar hot water and for industrial purposes.

Solar technologies can be classified as passive or active, depending on the method of intake, conversion and distribution of solar energy. Active solar techniques include solar thermal collectors and photovoltaic panels to harness the energy. Passive solar techniques include selecting materials, orienting to the Sun, light dispersing properties, and designing spaces that naturally circulate air.


Advantages and disadvantages of wind energy


Flow of air is used to run wind turbines which provide a source of clean and renewable energy for homes or business. Small wind energy devices generate power very cost effectively.

Wind turbines range from 600 kW to 5 MW of power. The power output is the cube of the wind speed, hence power output increases as the wind speed increases. Offshore and high altitude areas where winds are stronger are preferred for wind farms.

Advantages:

Wind energy is friendly to the surrounding environment,

Wind turbines take up less space than a power station.

The wind is free.

Wind turbines can generate energy in remote locations.

Disadvantages:

The winds unreliability factor, which can be too low to support a wind turbine or wind farm,

Wind turbines produce less electricity than fossil- fueled power station; hence multiple wind turbines are needed to make an impact.

Construction can be very expensive.

The noise pollution from commercial wind turbines is sometimes similar to a small jet engine.


Geothermal power energy


The earth contains a large amount of energy in the form of heat. Geothermal energy is obtained by using the earth's heat from kilometers deep into the Earth's crust or from some meters. All this geothermal energy has the potential to generate power to provide electricity.

Three different types of geothermal energy power plants are used to generate power: flash, dry steam and binary.

The best advantage of geothermal energy is that they are useful even in cold regions like Norway and Sweden by using ground source heat pumps.

Experience Weightlessness

Introduction to experiencing weightlessness

As we know that the earth attracts every another body towards its centre. The force with which the earth attracts another bodies is called the weight. The weight of the body on the earth is equal to the product of the mass of the body and the acceleration due to gravity of earth. Here we can say that the weight = mass × acceleration due to gravity = mg. The value of acceleration due to gravity (g) is not constant throughout the earth. The weight of the body changes as the value of the acceleration due to gravity changes. Here we discuss in which situation the weight of the body becomes zero that means the condition of the body is weightlessness.I like to share this Units for Acceleration with you all through my article.


Experiencing weightlessness and conditions related to it


The weight mg of the body is also known as the true weight or the static weight of the body. We become conscious for our weight, only when weight is opposed by some other object. Actually, the secret of measuring the weight of the body with the weighing machine lies in fact that as we place the body on the weighing machine, the weighing machine opposes the weight of the body. The reaction of the weighing machine gives the weight of the body. There are four main conditions in which the body becomes weightlessness. The four conditions are as follow:

(i) When the body falling freely under the gravity the weight of the body is zero. For example, a lift is falling freely; any ball falling from the tower etc. experiences the weightlessness.

(ii) When the satellite revolves in the orbit around the earth experiences weightlessness. The gravitational force acting towards the centre of the earth balances by the centripetal force acting on the body so that the weight is zero.

(iii) When the bodies are at null point in the outer space. After the certain height, the gravitational pull of the earth becomes less and it is more for moon so that the body will feel the attraction force towards the moon. At that particular height where the gravity of the earth balances by the gravity of moon, the body experiences weightlessness.

(iv) When we reach at the center of the earth, we feel weightlessness. As the value of the acceleration due to gravity at the centre of the earth is zero and so, the weight of the body at the centre of the earth is also zero.


Conclusion of experiencing weightlessness


Weightlessness causes very serious problems to the astronauts. It becomes quite difficult for them to control their movements. Everything in the artificial satellite has to be kept tied down. To overcome this problem we create the artificial gravity so that they do not feel the weightlessness.