Galaxy Definition

Introduction to galaxy definition:

We always observes that there are infinite numbers of stars in the sky. The question arises hat how are the stars distributed in the space. Astronomers have found that the starts are arranged in the huge groups. These groups are called the galaxies. The stars in the galaxy are held together by the gravitational attraction between them. Here we discuss about the galaxy.


A few points about Galaxy


Generally, a galaxy is the clusters of stars in the large amount. A component of the universe that has a huge group of stars and other celestial bodies bound together by the force of gravitation is called a galaxy. Apart from stars, a galaxy also has huge clouds of gases from which the new stars are born. A galaxy may have planets, moons, asteroids, comets and another celestial bodies. The number of stars in a galaxy can range about a million to hundred of billions. It is also estimated that there are over 100 billions galaxies in the universe and astronomers are discovering more every day. The galaxy in which our sun is located is called the Milky Way galaxy or Akashganga.


Types of galaxies


Galaxies have different shapes. Based on the shapes, mainly, three types of the galaxies are there, which are  Spiral galaxies, elliptical galaxies and irregular galaxies. In a spiral galaxy the stars forms a big spiral pinwheel. The Milky Way galaxy is a spiral galaxy. In an elliptical galaxy the stars are confined mainly in ellipsoid volume. An irregular galaxy does not have any particular shape.



Conclusion to galaxy


Most of the stars of the Milky Way galaxy lie in the disc shaped region, this region is called the galactic disc. The central part of the disc is thicker and bulges on both the sides. The density of stars in the bulge is much higher than that in the outer region of the galaxy. Milky Way galaxy is a large galaxy. The diameter of the galactic disc is about 100, 000 light years and its average thickness is about 70 light years.

Electricity Generation From Water

Introduction:

Electricity can be generated from water in two methods; one is the method where we use the potential energy of the water in dams using the water wheels. The other source of energy is capturing the energy from the ocean waves. The energy generated by the water is a renewable energy, as we know that water is present abundantly in the nature and there is no consumption of water during the generation of electricity from the water. Most of the countries rely on this method that is production of electricity using water because it is a renewable energy resources and gives sustainable energy.  The energy generated by the water is termed as the hydro electricity.


Sources of electricity generation


Dams: In this case whenever a dam is built at the beginning itself the tunnels are built where the water flows and these tunnels are lined with turbines. As we let out the water to flow through these tunnels the water flows over the turbines which are lined along the tunnels.As a result these turbines rotate,and thus electricity is generated.

Ocean waves: The electricity generated from the ocean is known as ocean wave power because this energy is generated by the oceanic waves. This is the process where the tidal energy is used to generate the electricity, whenever there is a high tide on the sea shore or the oceans there is lot of energy in these waves which is converted into electricity by running of the turbines. The water from the tides is stored and then this water is left over the turbines which in turn produce the electricity.


Run of the river: This is process where the natural elevations on the rivers are made use to produce the electricity. In this case the water is made to fall on the turbines which are placed at the bottom of the elevation of the river, it can be a natural or a man made elevation on the river. Here also the turbine are used to produce the electricity.

Light Measurement

There are many different units for Light Measurements. Let’s first discuss some of them.

1. Candela (cd)- It is the unit of Lumen Measurement of a light source in a specific direction, also called as candle. This intensity is perpendicular to the direction of the surface of a black body.
2. Foot candle (fc or ftc)- It is a unit of intensity which used to measure in lumens per square foot.
3. Lux (lx)-  It is the unit of illumination which equals to one lumen/ square metre.
4. End Foot candle- This unit is a measurement which is based on the focused beam only. It is a focal beam measurement from point A to point B at one-foot distance.
5. End Lumens- This measurement is based on a spot of light.


6. Luminance- Also called as Luminous Flux which is the quantity of light leaves the lamp and measured in lumens (lm).
7. Luminous (Light Level): It is the amount of light measured on the work plane in the lighted space. Remember a work plane is an imaginary horizontal, tilted or vertical line where the tasks in the space are performed.
8. Beam Lumens- It is the total flux in that region of space where the intensity is more than 50 percent of the maximum intensity.
9. Lux- It is a metric unit of measure for illuminance of a surface. One lux = one lumen/ square meter= 0.0929 footcandles.
10. Light Level- It is the measurement of intensity on a plane at a specific location known as illuminance which is measured in footcandles.
11. Efficiency—the measure of the luminous efficiency of a radiant flux which is expressed in lumens/ watt is equals to efficiency.
12. Watt- It is a measurement of electrical power which does not relate to the output level and defines as the rate of energy consumption by an electrical device in operating stage. Watts= Volts x Amps x Power Factor (PF)



The wavelength is a length of a function period which shows the distance between any two points with the same phase and measured in meter light.  Let’s discuss; ‘How to Measure Wavelength of Light’? It can calculate either from the energy or frequency by using the speed and Planck constants. Remember the energy is typically expressed in electron volt (eV) units and the frequency is expressed in Hertz where one Hz equals 1/sec. Therefore the relation between velocity, frequency and wavelength can be written as follows;

Velocity of Light = (wavelength) x (frequency)(meters) x (cycles per second or Hertz)
= (3 x 108 m/sec)

Initial Velocity

The first question that arises when we read about distance, speed and velocity is the basic difference between speed and velocity. Velocity is the directional quantity while speed is not. We have already discussed about the importance of direction while calculating vector quantities.Having problem with Formula for Velocity keep reading my upcoming posts, i will try to help you.

Velocity in simple terms can be defined as the distance covered per unit time in a particular direction. This means that here we are also taking the direction in consideration. If we were to define speed we could have said it the distance per unit time. We will not have mentioned the direction bit.

We can divide the velocity into two parts. These are final and the initial velocity. As it is clear from the name the In. velocity is basically the starting velocity of an object or a body while final velocity is the finishing velocity. It may seem confusing at first but is quite easy.


Let us take an example. If the car starts and attains a velocity of 30 kilometers per hour then the initial vel. Considered would be zero km per hour while the final velocity will be 30 km per hour after 4 hours in a particular direction say southwards. Calculate Initial Velocity is easy. We can directly use the equation of motion which says
v = u + a t - - - - - - -(1)
Here v is the final velocity
U is the initial velocity
A is the acceleration
And t is the time taken to attain the final velocity.
Also s = u t + ½ a t 2 - - - - - - - - -(2)
Here s is the distance covered in a particular time interval.
This is the Equation for Initial Velocity. There is yet another equation for its Calculating Initial Velocity. It is:
V2 = u2 + 2 a s - - - - - - - - - - -(3)
Let us assume a ball is rolling on a platform. It attains a velocity of 10 m per seconds with an acceleration of 4 m per second 2. The time taken is 2 seconds.
Let us try to calculate the initial velocity.  Take the first equation into consideration.
So v = u + a t
10 = u + 2 * 4
10 = u + 8
u = 2
So initial vel. is  2 metre per second.
You can also calculate it according to different values of s, a, v, t in different situations.

Velocity Mass Equation

Mass in special relativity

The term mass  in special relativity usually refers to the rest mass of the object, which is the Newtonian mass as measured by an observer moving along with the object. The invariant mass is another name for the rest mass of single particles. The more general invariant mass (calculated with a more complicated formula) loosely corresponds to the "rest mass" of a "system." Thus, invariant mass is a natural unit of mass used for systems which are being viewed from their center of momentum frame, as when any closed system (for example a bottle of hot gas) is weighed, which requires that the measurement be taken in the center of momentum frame where the system has no net momentum. Under such circumstances the invariant mass is equal to the relativistic mass (discussed below), which is the total energy of the system divided by c (the speed of light) squared. I like to share this Formula for Acceleration due to Gravity with you all through my article.

The concept of invariant mass does not require bound systems of particles, however. As such, it may also be applied to systems of unbound particles in high-speed relative motion. Because of this, it is often employed in particle physics for systems which consist of widely separated high-energy particles. If such systems were derived from a single particle, then the calculation of the invariant mass of such systems, which is a never-changing quantity, will provide the rest mass of the parent particle (because it is conserved over time).
Despite the convenience that the invariant mass is the same as the total energy of the system (divided by c2) in the center of momentum frame, the invariant mass of systems (like the rest mass of single particles) is also the same quantity in all inertial frames. Thus, it cannot be destroyed, and is conserved, so long as the system is closed. (In this case, "closure" implies that an idealized boundary is drawn around the system, and no mass/energy is allowed across it).


The term relativistic mass is also sometimes used. This is the sum total quantity of energy in a body or system (divided by c2). As seen from the center of momentum frame, the relativistic mass is also the invariant mass, as discussed above (just as the relativistic energy of a single particle is the same as its rest energy, when seen from its rest frame). For other frames, the relativistic mass (of a body or system of bodies) includes a contribution from the "net" kinetic energy of the body (the kinetic energy of the center of mass of the body), and is larger the faster the body moves. Thus, unlike the invariant mass, the relativistic mass depends on the observer's frame of reference. However, for given single frames of reference and for closed systems, the relativistic mass is also a conserved quantity.Although some authors present relativistic mass as a fundamental concept of the theory, it has been argued that this is wrong as the fundamentals of the theory relate to space-time. There is disagreement over whether the concept is pedagogically useful. The notion of mass as a property of an object from Newtonian mechanics does not bear a precise relationship to the concept in relativity.

For a discussion of mass in general relativity, see mass in general relativity. For a general discussion including mass in Newtonian mechanics, see the article on mass.

Used Laser Cutting Machine

Introduction to used laser cutting machines:

First we will discuss about LASER. LASER means the Light Amplification by Stimulated Radiation and Emission. The laser beams are highly energetic and highly coherent. There are different types of laser machines, which produces laser beams such as ruby laser, helium neon laser. There are different stages of  lasers. For example, ruby laser is the three stage laser and Helium neon is a four stage laser. Let us discuss about the used laser cutting machines. Please express your views of this topic Emp Bomb Effects by commenting on blog.



Use of laser cutting machines


The laser machines cut the materials by vaporizing the material at that particular place. The laser beam is focussed on the path of the size of thick human hair. In other words we can say that the laser beams be focussed on 0.005 inch and leaving vapours and ash to exhaust. We can cut the steel sheet in a desired shape by the use of laser cutting machines.

The laser beams can cut the diamond with the very fine cut. The cutting of the diamond in the fine mode is possible due to the laser cutting machines.


Factors relating to laser cutting machines


There are some factors in the laser cutting machines. The main factors are power of the laser beams, laser focusing, speed of cut, thickness of the material which is to be cut, etc. The power of the laser cutting machine is the main factor of the machine. If the power is more, then we cut deep inside the surface and more quicker. The laser cutting machine is of 50 Watt power. We can use the power ranging between 1% to 100%. Laser machine has more power as they starts up. So we have to keep warming the laser machines. The lasers have the working area of 12 inches by 24 inches. Is this topic Physics Projectile Motion Problems hard for you? Watch out for my coming posts.


Modes of cutting through a laser


The laser cutting machine has two modes of the cutting, one is called the vector mode and the other is called the raster mode. The mode which is used for designing in the cutting is called the vector mode. Rastering mode is used for the engraving purposes. The laser head of the laser cutting machines moves back and forth to cut a picture.


Conclusion for the laser cutting machines


Laser beam should be perfectly focused before use on any material. Generally the lens of the laser cutting machines has two inches focusing length. The lenses may be shorter or longer. Longer the lenses, lesser is the accuracy. It is used to cut the wood, paper, fibre glass, diamonds, etc.

Universe Infinite Finite

Introduction to universe infinite finite:

Before the study of this topic, the first question arises that what is universe. The space in which the galaxies, black holes, solar systems, suns, moons and millions of others celestial bodies is called universe. Ancient philosophers believed that earth is the centre of the universe, around which everything else in the universe revolved. They even thought that the earth to be flat in shape. To understand the creation of the universe, we had to first learn a lot about the earth and the solar system, galaxies and so on. Here we discuss how the universe is expanding. I like to share this Electromagnetic Pulse Effects with you all through my article.


Modern theories on Universe


There are several modern theories about the beginning of the universe and its future. Now the scientists think that the big bang theory offers the best explanation about the universe. This theory was proposed when the scientists concluded that the universe is expanding. In 1920, Professor Edwin Hubble observed that the frequency of light coming from far off galaxies decreased, i.e., the frequency of the light coming from the far off galaxies showed a red shift. Professor Edwin Hubble studied these red shifts carefully and concluded as follows:

All galaxies are moving away from each other.
The speed with which any two galaxies move away from each other is directly proportional to the distance between them. This is called the Hubble’s law. The larger the distance between two galaxies, faster they move away from each other.
In other words, from the observed red shift, the frequency of light coming from the far off galaxies, Professor Edwin Hubble concluded that the universe is expanding. Thus, the universe is infinite in size.


Conclusion on universe whether it is infinite or finite


The future of the universe is totally depending on the mass of the universe. If the mass is large enough, gravitational attraction will slow down the expansion and eventually stop it. After that, the galaxies will move towards each other due to the gravitational force between them. They will merge in the one lump of the super dense material. Again, a big bang will take place and a new universe will be created. Therefore, we will have an oscillating universe.