SATELLITES

The objects moving around a planet are called the satellites of that planet. The moon moves around the earth hence moon is a satellite of the earth. The moon is a natural satellite of the earth. The centripetal force must be provided for moon to move around the earth . Here the necessary centripetal force is provided by the gravitational force between the moon and the earth.
In the same way by providing necessary centripetal force by by the gravitational force between the earth and the object it is possible to make it to move around the earth . These days there are very large numbers of human beings made satellites i.e. artificial satellite moving around the earth in different orbit saving different purpose,such as transmission of tv and radio programs for the telecommunication purposes etc.
LAUNCHING SATELLITE'S:
When satellite are made to move away from the earth's gravitational field the minimum velocity required is 11.3k/s or 40320 km/hr. Using a single stage rocket it is not possible to have so much velocity. Hence for launching satellites multistage rockets are used. Generally for such purposes 3-stage rockets satellites is always kept at the rckets are used.
In the rockets satellites is always kept at the top of the third stage . During launching of the rockets the burnt fuels comes out from the nozzle of the rocket, Then according to the third law of motion the opposite reaction that exceeds rockets weight lift and moves the rocket in upward direction. The rocket accelerates upwards and rises vertically upward so that it passes through the denser atmosphere with least time. Then first stage of the second stage makes the rocket to move with high velocity. After moving through certain distance attaining the height speed the second stage of the rocket also detached and falls back. Using the final third stage of the rocket the satellites is turned in the horizontal direction and is given proper speed for the satellite so that it remains on the orbit.Then the satellite moves around the earth in a closed orbit.

PHOTOMETRY

Light is a physicaal quantoty. Hence as other physical quantity light is also must be measurable. The branch of light that deals with the measurement of light called photometry. In photometry, we have to know about some definitions as given below.
LUMINOUS ENERGY: Light is a measurable physical quantity. Just as electric current flows through a conducting wire the light is also the flow of flux or radiant energy called the luminous energy.Light can be taken as aform of energy since light can be converted to other forns of energy and similarly other forms of energy can also be converted to light for examples:

1. PHOTOCEL:It converts light to electrical energy.
2. SOLAR BATTERY:It converts light to electrical energy.
3. BULBS:It changes electrical energy to light energy and heat .

Hence according to the principle of conservation of energy, light must be a form of energy.

Terrestrial Magnetism: Exploring Earth's Magnetic Field and Its Significance

Introduction:
In early times people thought that the north started attracting the north pole of the magnetic compass. But later a physician William Gilbert interested in scientific experiments suggested that the earth itself behaves like a huge magnet. For verification, he made a clay sphere and kept a long lode of some magnets inside the sphere with two poles one at the top and the other at the bottom. Then he made a dipping needle compass that could dip and down only and held it near one person of the lodestone. He found that the needle pointed towards the center of the sphere. When he held the dipping needle at the center of the sphere the needle set parallel to the horizontal. When he held the dipping needle near the equator of the lodestone, the needle was itself parallel to the line through the two poles. Gilbert concluded that the earth is a magnet dipping needle that should till down More and more as the needle is carried north and that it should point straight down at the magnetic equator, the dip of the needle is zero. Thus the two poles at which the needle shows 90 degrees are known as the poles of the Earth. They are not at the same points as the geographical poles. The angle between the two lines joining the two magnetic poles and the other joining the two geographical axes makes about 17 degrees. The line joining the points where the angle of inclination is zero is called the magnetic equator.

Characteristics of Earth's Magnetic Field:

Magnetic Dipole: Earth's magnetic field can be approximated as a magnetic dipole, with a north magnetic pole near the geographic South Pole and a south magnetic pole near the geographic North Pole. This results in a magnetic axis that is tilted concerning the rotational axis of the Earth.

Magnetic Declination: Magnetic declination is the angle between true north and magnetic north. It varies based on geographic location and changes over time due to the movement of Earth's magnetic field. Accurate knowledge of magnetic declination is essential for navigation and compass use.

Magnetic Intensity: Magnetic intensity refers to the strength of Earth's magnetic field at a specific location. It is commonly measured in units of tesla (T) or its subunit, nanotesla (nT).

Magnetic Anomalies: Earth's magnetic field exhibits variations known as magnetic anomalies. These anomalies can occur due to variations in the composition and magnetization of rocks beneath the Earth's surface. Studying these anomalies provides insights into geological structures, mineral exploration, and plate tectonics.

Measurement Techniques:

Scientists employ various methods to measure and study Earth's magnetic field:

Magnetometers: Magnetometers are instruments used to measure the strength and direction of magnetic fields. They range from simple handheld compasses to sophisticated devices like fluxgate magnetometers and proton magnetometers, capable of providing detailed magnetic field data.

Magnetic Observatories: Permanent magnetic observatories are established at various locations worldwide to monitor and record Earth's magnetic field over time. These observatories contribute to global magnetic surveys and aid in detecting long-term changes and magnetic disturbances.

Satellite Missions: Space-based missions, such as the European Space Agency's Swarm mission, utilize satellite magnetometers to gather high-precision magnetic field measurements. These missions enable the mapping of Earth's magnetic field on a global scale, providing valuable data for scientific research.

Significance and Applications:

Terrestrial magnetism holds immense significance across scientific disciplines and practical applications:

Geophysics and Earth Science: Studying terrestrial magnetism helps us understand Earth's internal structure, including the composition of the core, mantle, and lithosphere. It provides insights into the dynamics of the Earth's interior, plate tectonics, and the history of the planet.

Navigation and Compass Use: Earth's magnetic field has long been utilized for navigation. Compasses rely on the magnetic field to indicate a direction, allowing mariners, aviators, and hikers to navigate accurately.

Magnetic Field Protection: Understanding the behavior of Earth's magnetic field is crucial for protecting sensitive electronic devices, power grids, and communication systems from the effects of geomagnetic storms and solar flares.

Archaeology and Paleomagnetism: The study of ancient magnetic fields preserved in rocks, sediments, and archaeological artifacts, known as paleomagnetism, helps in reconstructing Earth's past magnetic field. This field provides valuable insights into geological time scales, past continental drift, and the movement of tectonic plates.

Space Weather and Ionospheric Studies: Terrestrial magnetism plays a significant role in space weather research. Variations in Earth's magnetic field interact with charged particles from the Sun, resulting in phenomena such as auroras and geomagnetic storms. Understanding these interactions is crucial for satellite operations, space missions, and radio communications.

Environmental Monitoring: Changes in Earth's magnetic field can be indicative of environmental factors such as underground water flows, volcanic activity, and seismic events. Monitoring magnetic field variations assists in detecting and assessing these environmental changes.

Magnetic Resonance Imaging (MRI): Medical imaging techniques like MRI rely on the principles of magnetic fields and their interaction with atoms in the human body. Terrestrial magnetism provides a foundation for understanding the behavior of magnetic fields in these medical applications.

Conclusion:

Terrestrial magnetism, the study of Earth's magnetic field, is a fascinating field of research with diverse applications. From its origin in the Earth's core to its effects on navigation, geophysics, and space weather, understanding the properties and characteristics of Earth's magnetic field provides valuable insights into our planet's past, present, and future. Through the use of sophisticated measurement techniques and ongoing scientific investigations, we continue to unravel the mysteries of terrestrial magnetism and its profound influence on our lives.

DEPTH KNOWLEDGE MECHANICS

AXIAL VECTOR:
Those vectors related with rotation or responsible for rotation.Example angular momentum,angular velocity etc.
POLAR VECTOR:
Those vector related with translation or responsible for translation .Example force,displacement,velocity etc.

• A vector must be changed if we change its magnitude ,direction or both .
• A vector is not changed if it is slide parallel and due to change of co-ordinate x-axis.

Q} A vector is not changed if
ans: slides parellely.
ADDITION OF TWO VECTORS:

• Resultant of any two vectors lies along major diagonal when the angle between both vector less than 90 degree.
• Resultant lies along minor diagonal when the Angle between both vector is obtuse.
• Minimum number of unequal vectors lying on same plane required to make R=0 is 3.
• Minimum number of unequal vectors not lying on same plane required to make R=0 is 4.
  

CONCEPT IN SOUND

1. WAVE AND SOUND

WAVE:Way is a disturbance,which can be transfer from one place to another place to the another place due to repeated periodic motion of the particles of the medium about their mean position.
LONGITUDINAL WAVE +TRANSVERSE WAVE=ripple wave

• Wave produced in a string=1 dimensional
• Wave produced in water=2 dimensional
• Sound and light wave=3dimensional

Wave are two types :

1. Mechanical wave
   
2. Non mechanical wave

• For the propagation mechanical wave, elasticity as well as density of medium is required that's why mechanical wave is also known as elastic wave.

• In a non -mechanical wave,vibration takes place in both electric field as in magnetic field that's why non-mechanical wave is also known as electromagnetic wave.

• Medium is required for the propagation of mechanical wave. For example wave produce in a string ,spring,sonometer wire, tuning fork and sound wave etc.
• There is no requirement of medium for the propagation of non-mechanical wave.Example:light,X-rays, Gama rays, radiation and radio waves.

1. MECHANICAL WAVE:

Mechanical wave are two types:

• Transverse wave
  
• Longitudinal wave

If wave is longitudinal,it must be a mechanical wave and if wave is mechanical then

• It may be longitudinal wave.
• It may be transverse wave.
• It may or may not be longitudinal.
• It may or may not be transverse.

1. NON-MECHANICAL WAVE:

All non -mechanical waves are only transverse in nature
If wave is non-mechanical then must be a transverse wave and wave is non-mechanical wave then

• It may be mechanical wave .
• It may be non-mechanical wave.
• It may or may not be mechanical wave.
• It may or may not be non-mechanical waves.
  

DEPTH KWOWLEDGE IN ELECTROSTATICS

COLUMBUS LAW:

• Two charges express Columbus force due to interaction electric lines of force produce by charges.
• Magnitude of Coulomb;s force on the two charges will be always equal and opposite direction even charges and their masses may be or may not be equal and charges may be like or unlike.
• Force with negative sign represent attractive force and the convention is applied only in magnitude form.
• Above convention is applied only for Coulomb force, gravitational force and magnitude force between two current carrying wire.
• An electron is accelerating with potential of 1volt. Then find kinetic energy and speed gained by electron. Electron, proton,deuteron,Triton accelerating with potential of 1volt kinetic energy gained=1Ev=1.6^-19J.
• Insulator and conductor commonly called as dielectric is used as between charges to very Coulomb force and other electrostatics quantities.
• For pure water K=81(maximum) where K is relative permittivity or dielectric constant.
• For perfect insulator k=o i.e. perfect insulator cannot be charged by any method.
• Dielectric constant of medium epsilon cannot be equal to 1.
• Coulomb force will be maximum if between the charges is air or vacuum and after putting single dielectric completely between the charges then force, decrees by k time.
• If a conductor is kept completely or partially between the charges than Coulomb force decreases to zero.Since electric lines of force produced by charge cannot interact.
• Conductor constant is defined as property of medium which oppose electric lines of force.
• Conversation of charges is consequence of principle of continuity.
• Another left things i will write in another article.
  

Electric potential

If a small positive test charge is placed at a point in an electric filed due to a positive source charge moves away from the source charge. Similarly, if the positive test charge is placed at a point in an electric field due to negative source source charge, the test charge is is found to move towards the source charge. These statements suggest that every point in an electric field have potential. The potential of a point in an electric field is called electric potential.
The electric potential is analogous to the gravitational potential .The electric potentials at different points in the electric field may be different.When a mass moves from one to another point, the gravitational potential energy of the gravitational field is converted into the kinetic energy of the mass. Similar is the case in case of charge moving in an electric Field. When a charge moves in an electric field., the potential energy of the two points in the electric field is converted into the kinetic energy of the charge. Similarly, if a charge is to move against an electric field, the kinetic energy of the charge is converted into the electric potential energy. The electric potential at a point in an electric field is defined as the amount of work done in bringing a unit positive charge from infinity to that point.

Brief introduction to optics

Light is a from of energy stimulates the sensation of vision and makes us see objects around us. Light is emitted by bodies which are heated to very high temperature,such as glowing electric bulb,burning candles,sun,etc.Light can travel through vacuum, It does not require material medium to travel from one place to other.
When light falls on an object,it is party reflected. We see the objects only when the light reflected from the objects enters into our eyes. Regarding the nature of light,Newton put forward the corpuscular theory of light. According to this theory, light consists of tiny elastic particles called corpuscles. A light source emits such corpuscles in all directions when these cor pules strikes an objects, they are partly reflected and the reflected corpuscles enter into our eyes and we see the objects. On the basis of this theory, phenomena like rectilinear propagation,reflection and refraction of light can be explained. At about the same time Huygens proposed wave theory of light. According to this theory, light is propagated in the form of wave through either which was assumed to be present everywhere.This theory explain besides reflection, refraction of light other phenomena like interference,diffraction and polarisation of light. But because of newton's popularity at that time, his corpuscular theory prevailed, and the wave theory remained in the black ground for over a century.
Later, experiments on the measurements of the velocity of light in different media showed that the velocity of light in denser medium, like water or glass, is smaller than the velocity of light in air. According to Newton's corpuscular theory, the velocity of light in denser medium should be greater than that in rarer medium with these experimental results, wave theory of light become general acceptance from scientific communities.
Still latter, it was found that when light of suitable frequency is incident on certain metals, electrons are emitted. This phenomenon could be explained only by assuming that light is absorbed or emitted in the form of quantum of energy .Each quantum of energy is a packet of energy called photon .Photons behave as particles.