wbcs.
Detailed information about WBCS which is the premier government service of the Government of West Bengal and it is also informative for existing WBCS officers.
Articles
WBCS Preliminary Examination: General Science
2010-06-08 13:44:55
General Science is one of the most important segments of the WBCS Preliminary paper. Therefore, an extensive study of all three sections of General Science can give a WBCS aspitants the winning edge. For the WBCS Preliminary Examination, one must get hold of all the three sections of General Science-Physics, Chemistry and Biology. Click on the respective link for details:Physics: Units and Measurement.Mechanics.Work, Power and Energy.Properties of matterWaves HeatElectricity and MagnetismLightSoundAtomic PhysicsSpace ScienceChemistryBiology
2010-06-08 13:44:55
General Science is one of the most important segments of the WBCS Preliminary paper. Therefore, an extensive study of all three sections of General Science can give a WBCS aspitants the winning edge. For the WBCS Preliminary Examination, one must get hold of all the three sections of General Science-Physics, Chemistry and Biology. Click on the respective link for details:Physics: Units and Measurement.Mechanics.Work, Power and Energy.Properties of matterWaves HeatElectricity and MagnetismLightSoundAtomic PhysicsSpace ScienceChemistryBiology
WBCS Preliminary ( Physics): Space Science
2010-06-08 13:43:47
The limitless expanse of space around us consisting of solar system, galaxies, stars and planets etc, is called universe. The age of the universe is estimated to be (1-2)X1010 years.The vast collection of billions of stars along with the vast amount of hydrogen and dust in an isolated in the universe is called galaxy. There are nearly 1010 galaxies which are the building block of the vast universe. Galaxies are not fixed in the universe but are moving outwards.Our Solar System is a part og thr galaxy called the "milky Way". The nearest galaxy to our own galaxy is Andromeda galaxy. The Milky way has three main parts: a nuecleus, a disc and a halo. It contains about 100,000 milion stars.The diameter of the Milky way is neraly 120,000 light years.Nebula, which appear in the sky as bright spot
2010-06-08 13:43:47
The limitless expanse of space around us consisting of solar system, galaxies, stars and planets etc, is called universe. The age of the universe is estimated to be (1-2)X1010 years.The vast collection of billions of stars along with the vast amount of hydrogen and dust in an isolated in the universe is called galaxy. There are nearly 1010 galaxies which are the building block of the vast universe. Galaxies are not fixed in the universe but are moving outwards.Our Solar System is a part og thr galaxy called the "milky Way". The nearest galaxy to our own galaxy is Andromeda galaxy. The Milky way has three main parts: a nuecleus, a disc and a halo. It contains about 100,000 milion stars.The diameter of the Milky way is neraly 120,000 light years.Nebula, which appear in the sky as bright spot
WBCS Preliminary ( Physics): Atomic Physics
2010-06-07 14:08:42
An atom is the smallest particle of the element that can exist independently and retain all its chemical properties.Dalton’s atomic theory , which suggested that the atom was indivisible and indestructible. But the discovery of two fundamental particles (electrons and protons) inside the atom, led to the failure of this aspect of Dalton’s atomic theory.Thomson proposed that: An atom consists of a positively charged sphere and the electrons are embedded in it. The negative and positive charges are equal in magnitude. So, the atom as a whole is electrically neutral.Rutherford’s alpha-particle scattering experiment led to the discovery of the atomic nucleus. Rutherford’s model of the atom proposed that a very tiny nucleus is present inside the atom and electrons revolve around this nu
2010-06-07 14:08:42
An atom is the smallest particle of the element that can exist independently and retain all its chemical properties.Dalton’s atomic theory , which suggested that the atom was indivisible and indestructible. But the discovery of two fundamental particles (electrons and protons) inside the atom, led to the failure of this aspect of Dalton’s atomic theory.Thomson proposed that: An atom consists of a positively charged sphere and the electrons are embedded in it. The negative and positive charges are equal in magnitude. So, the atom as a whole is electrically neutral.Rutherford’s alpha-particle scattering experiment led to the discovery of the atomic nucleus. Rutherford’s model of the atom proposed that a very tiny nucleus is present inside the atom and electrons revolve around this nu
WBCS Preliminary(Physics): Sound
2010-06-06 10:21:54
Sound is a form of energy and like all other energies, sound is not visible to us. It produces a sensation of hearing when it reaches our ears. Sound can not travel through vacuum. Sound is produced due to vibration of different objects.The matter or substance through which sound is transmitted is called a medium. It can be solid, liquid or gas. Sound moves through a medium from the point of generation to the listener. In longitudinal wave the individual particles of the medium move in a direction parallel to the direction of propagation of the disturbance. The particles do not move from one place to another but they simply oscillate back and forth about their position of rest. This is exactly how a sound wave propagates, hence sound waves are longitudinal waves. Sound travels as successiv
2010-06-06 10:21:54
Sound is a form of energy and like all other energies, sound is not visible to us. It produces a sensation of hearing when it reaches our ears. Sound can not travel through vacuum. Sound is produced due to vibration of different objects.The matter or substance through which sound is transmitted is called a medium. It can be solid, liquid or gas. Sound moves through a medium from the point of generation to the listener. In longitudinal wave the individual particles of the medium move in a direction parallel to the direction of propagation of the disturbance. The particles do not move from one place to another but they simply oscillate back and forth about their position of rest. This is exactly how a sound wave propagates, hence sound waves are longitudinal waves. Sound travels as successiv
WBCS Preliminary (Physics): Light
2010-06-01 12:22:30
To understand light you have to know that what we call light is what is visible to us. Visible light is the light that humans can see. Other animals can see different types of light. Dogs can see only shades of gray and some insects can see light from the ultraviolet part of the spectrum. As far as we know, all types of light move at one speed when in a vacuum. The speed of light in a vacuum is 299,792,458 meters per second.Any medium through which light can travel is an optical medium. If this medium is such that light travels with equal speed in all directions, then the medium is called a homogeneous medium. The homogeneous media through which light can pass easily, are called transperant media. The media through which light cannot pass, are called opaque media. Again the media through w
2010-06-01 12:22:30
To understand light you have to know that what we call light is what is visible to us. Visible light is the light that humans can see. Other animals can see different types of light. Dogs can see only shades of gray and some insects can see light from the ultraviolet part of the spectrum. As far as we know, all types of light move at one speed when in a vacuum. The speed of light in a vacuum is 299,792,458 meters per second.Any medium through which light can travel is an optical medium. If this medium is such that light travels with equal speed in all directions, then the medium is called a homogeneous medium. The homogeneous media through which light can pass easily, are called transperant media. The media through which light cannot pass, are called opaque media. Again the media through w
WBCS Preliminary(Physics): Magnetism and Electricity
2010-05-29 11:21:03
MAGNETISM: The word magnet is derived from the name of an island in Greece called Magnesia where magnetic ore deposits were found, as early as 600 BC. Magnetite, an iron ore, is a natural magnet. It is called lodstone.When a bar magnet is freely suspended, it points in the north-south direction. The tip which points to the geographic north is called the north pole and the tip which points to the geographic south is called the south pole of the magnet. There is a repulsive force when north poles ( or south poles ) of two magnets are brought close together. Conversely, there is an attractive force between the north pole of one magnet and the south pole of the other.The properties of a magnet are it attracts small piece of iron towards it.it always cmes to rest in north-south direction when s
2010-05-29 11:21:03
MAGNETISM: The word magnet is derived from the name of an island in Greece called Magnesia where magnetic ore deposits were found, as early as 600 BC. Magnetite, an iron ore, is a natural magnet. It is called lodstone.When a bar magnet is freely suspended, it points in the north-south direction. The tip which points to the geographic north is called the north pole and the tip which points to the geographic south is called the south pole of the magnet. There is a repulsive force when north poles ( or south poles ) of two magnets are brought close together. Conversely, there is an attractive force between the north pole of one magnet and the south pole of the other.The properties of a magnet are it attracts small piece of iron towards it.it always cmes to rest in north-south direction when s
WBCS Preliminary ( Physics): Heat
2010-05-27 11:51:17
Temperature is a relative measure, or indication of hotness or coldness. Heat is the form of energy transferred between two (or more) systems or a system and its surroundings by virtue of temperature difference. The SI unit of heat energy transferred is expressed in joule (J) while SI unit of temperature is kelvin (K), and °C is a commonly used unit of temperature.Thermometer is a device used for measuring temperatures. The two familiar temperature scales are the Fahrenheit temperature scale and the Celsius temperature scale. The Celsius temperature (tC) and the Farenheit temperare (tF) are related by: tF = (9/5) tC + 32In principle, there is no upper limit to temperature but there is a definite lower limit- the absolute zero. This limiting temperature is 273.16° below zero on the celsiu
2010-05-27 11:51:17
Temperature is a relative measure, or indication of hotness or coldness. Heat is the form of energy transferred between two (or more) systems or a system and its surroundings by virtue of temperature difference. The SI unit of heat energy transferred is expressed in joule (J) while SI unit of temperature is kelvin (K), and °C is a commonly used unit of temperature.Thermometer is a device used for measuring temperatures. The two familiar temperature scales are the Fahrenheit temperature scale and the Celsius temperature scale. The Celsius temperature (tC) and the Farenheit temperare (tF) are related by: tF = (9/5) tC + 32In principle, there is no upper limit to temperature but there is a definite lower limit- the absolute zero. This limiting temperature is 273.16° below zero on the celsiu
WBCS Preliminary (Physics): Waves
2010-05-27 11:37:15
WAVES: There are three types of waves: Mechanical waves require a material medium to travel (air, water, ropes). These waves are divided into three different types. Transverse waves cause the medium to move perpendicular to the direction of the wave.Longitudinal waves cause the medium to move parallel to the direction of the wave. Surface waves are both transverse waves and longitudinal waves mixed in one medium. Electromagnetic waves do not require a medium to travel (light, radio). Matter waves are produced by electrons and particles. A point of maximum positive displacement in a wave, is called crest, and a point of maximum negative displacement is called trough.Measuring Waves: Any point on a transverse wave moves up and down in a repeating pattern. The shortest time that a point takes
2010-05-27 11:37:15
WAVES: There are three types of waves: Mechanical waves require a material medium to travel (air, water, ropes). These waves are divided into three different types. Transverse waves cause the medium to move perpendicular to the direction of the wave.Longitudinal waves cause the medium to move parallel to the direction of the wave. Surface waves are both transverse waves and longitudinal waves mixed in one medium. Electromagnetic waves do not require a medium to travel (light, radio). Matter waves are produced by electrons and particles. A point of maximum positive displacement in a wave, is called crest, and a point of maximum negative displacement is called trough.Measuring Waves: Any point on a transverse wave moves up and down in a repeating pattern. The shortest time that a point takes
WBCS Preliminary(Physics): Properties of matters
2010-05-26 10:41:28
Properties of matters: A matter can neither be created nor it can be destroyed but it can be transformed from one state to another. Matter is made of basic building blocks commonly called elements which are 112 in number. The matter is made of only one kind of element then the smallest unit of that element is called an atom. If the matter is made of two or more different elements then the smallest unit of matter is called a molecule. Molecule is defined as the smallest unit of matter which has independent existence and can retain complete physical and chemical properties of matters.According to kinetic theory of matter: molecules are in the state of continuous motion in all possible directions and hence they posses kinetic energy which increases with the gain of heat energy or rise in temp
2010-05-26 10:41:28
Properties of matters: A matter can neither be created nor it can be destroyed but it can be transformed from one state to another. Matter is made of basic building blocks commonly called elements which are 112 in number. The matter is made of only one kind of element then the smallest unit of that element is called an atom. If the matter is made of two or more different elements then the smallest unit of matter is called a molecule. Molecule is defined as the smallest unit of matter which has independent existence and can retain complete physical and chemical properties of matters.According to kinetic theory of matter: molecules are in the state of continuous motion in all possible directions and hence they posses kinetic energy which increases with the gain of heat energy or rise in temp
WBCS Preliminary( Physics): Work, Power and Energy
2010-05-22 06:23:37
When a force acting on a body produces a change in the position of the body, work is said to be done by the force. Work done on an object is defined as the magnitude of the force multiplied by the distance moved by the object in the direction of the applied force. The unit of work is joule: 1 joule = 1 newton X 1 metre. Work done on an object by a force would be zero if the displacement of the object is zero.Power is defined as the rate of doing work. Power=(work done) / (time taken). The SI unit of power is watt. 1 W = 1 Joule/second. The unit of power is also horse power. It is the power of an agent which can work at the rate of 550 foot pounds per second or 33,000 foot pounds pwe minute. 1 horse power=746 watts.An object having capability to do work is said to possess energy. Energy has
2010-05-22 06:23:37
When a force acting on a body produces a change in the position of the body, work is said to be done by the force. Work done on an object is defined as the magnitude of the force multiplied by the distance moved by the object in the direction of the applied force. The unit of work is joule: 1 joule = 1 newton X 1 metre. Work done on an object by a force would be zero if the displacement of the object is zero.Power is defined as the rate of doing work. Power=(work done) / (time taken). The SI unit of power is watt. 1 W = 1 Joule/second. The unit of power is also horse power. It is the power of an agent which can work at the rate of 550 foot pounds per second or 33,000 foot pounds pwe minute. 1 horse power=746 watts.An object having capability to do work is said to possess energy. Energy has