Monday, January 17, 2011
LOCOMOTION IN ANIMALS
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Locomotion in animals is common, - organs which help in movement in common animals like - Mammals, insects, birds, fish, earthworm- Different kinds of movements, Movement in human beings- Muscles, joints, ligaments, tendons, cartilage joints in human body- different kinds of joints; Muscles work in pairs to produce movement , Difference between movement and lococmotion, movement in plants- phototropism, geotropism, hydrotropism- Positive and negative responses to the stimuli, Thigmotropism, Tropic and nastic movements, Movement of microscopic living things- Amoeba, paramecium, Euglena
Cranium - the part of skeleton that encloses the brain
Geotropism - movement of plant parts in response to force of gravity
Hydrotropism- movement of plant parts in response to moisture
Nastic movements- nondirectional plant movements in response to environmental stimuli
Phototropism- movement of plant parts in response to light
Skeleton - the hard framework that supports the body
Thigmotroprism- growth in response to touch
Tropic movements- directional plant movements in response to some environmental stimuli where direction of movement is determined by the direction of stimulus.
Friday, January 14, 2011
IMPEDANCE MATCHING
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By the matching of impedances we understand a selection of impedances between different media in such a way tha maximum transfer of energy takes place from one medium to the other. This is essential requirement in many practical situations. Thus, impedance matching represents a very important practical problem via -a - vis energy transfer
My dear friends, here today i will tell some good about this topic,
By the matching of impedances we understand a selection of impedances between different media in such a way tha maximum transfer of energy takes place from one medium to the other. This is essential requirement in many practical situations. Thus, impedance matching represents a very important practical problem via -a - vis energy transfer
i) Long distance cables - carrying energy have many lengths of wire joined end to end. These cables must be accurately matched at all joints, so that there is no wastage from energy reflection.
ii) A loudspeaker - has to be matched to the impedance of the power output of an amplifier by choosing the correct turns ratio on the coupling transformer. The amplifier gives us am amplified signal of the input signal (voice, music)
iii) The power transfer from a generator to ta circuit or electrical network is a maximum when the generator impedance is carefully matched with the circuit load.
The insertion of a coupling element between two mismatched impedances is of fundamental importance. It finds applications in many branches of physics, engineering. Such systems also exist in optics. We describe the physics of impedance matching by taking the case of mechanical waves on a string, but the results can be taken as valid for all kinds of waves.
We know that at a joint of two different impedances, there is a definite reflection of incident energy of the wave. Such impedances are called mismatching.
Monday, January 10, 2011
ATMOSPHERE AND ITS LAYERS
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1. Troposphere - This layer is extended upto 8 to 14 kms from the surface of the earth. This layer act as a medium for growth for plants and animals, all living things live on this layer, all plants grow on this layer, This layer become turbulent due to different temperature changes, all the season changes in this layer.
Atmosphere and its layers - We live on earth and there is air around us, and this blanket of air around us is known as atmosphere, Atmosphere is extended upto 800 kms from the surface of the earth. The air near the earth surface is denser and as we go higher and higher, its density decreases and it become thinner and thinner. Atmosphere mainly have five layers.
1. Troposphere - This layer is extended upto 8 to 14 kms from the surface of the earth. This layer act as a medium for growth for plants and animals, all living things live on this layer, all plants grow on this layer, This layer become turbulent due to different temperature changes, all the season changes in this layer. 2. Stratosphere - This layer extended upto 50 kms from the surface of the earth. It provide good atmosphere for aeroplanes and helicoptors. Ozone layer is also present in this layer, this ozone layer protects us from harmful UV radiations coming from the sun, if this radiation reaches on earth, the people will suffer from skin cancer.
3. Mesosphere -- This layer extended upto 85 kms from the surface of the earth. In this layer all the heavenly bodies like stars, comets are present, very big rocks which are known as meteoroid are present in this layer, When this big burning rocks also knows as shooting stars enter in this layer, there layers reduces them in their size.
4. Ionosphere - This layer is also known as thermosphere, and is extended upto 640 kms from the surface of the earth, so, just because of excessive heat in it, as the sun heat this layer upto 1500 degree celcius, This layer also having atoms and molecules, due to heat of sun, these atoms and molecules get ionized and releases ions.
5. Exosphere - This layer is extended upto 800 kms from the surface of the earth. This layer is external layer
Sunday, January 9, 2011
VELOCITIES ASSOCIATE WITH WAVELENGTH
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Often we come across different types of velocities, associated with wave motion, in one way or the other. For instance, we talk about the 1) particle -velocity, 2) wave velocity or phase -velocity and group velocity. Each has got a distinct definition as well as physical meaning for it. Before we proceed to discuss different types of velocities, it is worthwhile to bear in mind that a wave motion is a collective response of a large number of oscillators through which the disturbance goes, one by one,. Also, each of these oscillators undergoes a simple harmonic motion (S.H.M), at its own location. The very important fact here is that these individual oscillators of the medium, through which the wave progresses / advances, do not progress move along with the traveling wave. The motion of these oscillators about their mean positions can be transverse or longitudinal. What we observe as a wave motion is the locus of different particle phases. In other words, the waves as observed by us are the phase relationships of different particle oscillators coupled and not their progressive motion through the medium they constitute.
Often we come across different types of velocities, associated with wave motion, in one way or the other. For instance, we talk about the 1) particle -velocity, 2) wave velocity or phase -velocity and group velocity. Each has got a distinct definition as well as physical meaning for it. Before we proceed to discuss different types of velocities, it is worthwhile to bear in mind that a wave motion is a collective response of a large number of oscillators through which the disturbance goes, one by one,. Also, each of these oscillators undergoes a simple harmonic motion (S.H.M), at its own location. The very important fact here is that these individual oscillators of the medium, through which the wave progresses / advances, do not progress move along with the traveling wave. The motion of these oscillators about their mean positions can be transverse or longitudinal. What we observe as a wave motion is the locus of different particle phases. In other words, the waves as observed by us are the phase relationships of different particle oscillators coupled and not their progressive motion through the medium they constitute. 1) The Particle velocity - It is simply the velocity with which the simple harmonic oscillator moves about its mean or equilibrium position. As already discussed, this motion can be transverse or longitudinal direction of wave motion.
2) The wave velocity or Phase velocity - As we all know, crests and troughs represent planes of equal phase. the wave or phase velocity has been defined as the velocity with which planes of constant phase advance through the given medium.
3) The group velocity- It is an established fact that waves rarely occur/exist as single monochromatic components. Instead that , what we have is a superposition of a number of waves of different characteristics. The resulting composite entity is called a wave group.
Saturday, January 8, 2011
TYPES OF WAVES
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Well, one of the easiest and simplest ways to demonstrate the formation of waves is to hold the loose end of a rope which is fixed at the other end and to move it quickly up and down. Crests and troughs of the waves advance towards the fixed end of the rope. If the rope is very long, we can observe such a crest or trough. For the formation of progressive waves, we have a long unlimited rope , but if the medium is limited, of finite extent as we have in the case of a violin having a small string, fixed at both in ends, an interesting thing happens.
The progressive waves traveling on the string will get reflected at both fixed ends. Due to the superposition of incoming and reflected waves along the string results in the formation of standing waves. Standing waves or stationary waves are therefore formed /produced by the simultaneous transmission of two identical wave motions in opposite directions. Remember, we are talking about the mechanical waves. EM- waves like radio-waves, X-rays, light waves etc. are a class of their own and can travel even without a material medium. Mechanical waves are of two types:-
1) Transverse waves - are the waves in which the vibration of displacement takes place in a plane at right angles to the direction of propagation of the wave. Even non -mechanical waves are transverse in character. Waves on a stretched string are of this type only, as also the waves produced in a string.
2) Longitudinal waves- are the waves in which the vibration or displacement take place in the direction of propagation of the waves, sound waves and waves in a long spring the free end of which is pulled or pushed along its length fall in this category.
ELECTRICAL OSCILLATOR
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Before begin with, suppose the capacitor is fully charged, with magnitude of charge q0 on each plate, with the help of the battery B AND key K. Now breaking the battery ckt, the charged capacitor is connected across the inductor through the other key K. The capacitor will begin to discharge through the coil. The flow of charge from C through L constitutes a current I. This changing current sets up a magnetic field around the coil L. Soon, a stage comes when C is fully discharged and the field around L is saturated. The variations of magnetic field in the coil give rise to self induced emf which according to Lenz's law is with polarity opposite to that on the capacitor plates a little while ago.This back end recharges the neutral capacitor, plates acquire charge in opposite sense now. In the absence of resistance in this ckt., the energy of the electrical system remains constant and is exchanged between the MAGNETIC field energy stored in the coil and the ELECTRIC field energy stored between the plates of the capacitor.
Again, the process of discharging begins through the coil but the direction of current is reversed. A magnetic field is again set up around the coil, but with opposite polarity, till it reaches a saturation point and the capacitor is fully discharged The variations of magnetic flux again set up an induced emf in the coil. The induced current then recharges the capacitor to the saturation level of charge on its plates, and we regain the original starting stage.
Again, the process of discharging begins through the coil but the direction of current is reversed. A magnetic field is again set up around the coil, but with opposite polarity, till it reaches a saturation point and the capacitor is fully discharged The variations of magnetic flux again set up an induced emf in the coil. The induced current then recharges the capacitor to the saturation level of charge on its plates, and we regain the original starting stage.
Friday, January 7, 2011
ROLE OF ELASTICITY AND INERTIA SUMMARY
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c) A mass (m) attached to the free end of a fixed spring moving back and forth on a frictionless floor.
A small displacement from its equilibrium position sets up a restoring force, this force is proportional and acts in such a direction towards the equilibrium position.
Dear, now let us again take a closer look at some of the physical systems in motion ;
a) A simple pendulum with a swinging mass m at the end of a fixed light string of length l.
b) a torsional pendulum disc supported by and swinging about the same suspension wire/string.
c) A mass (m) attached to the free end of a fixed spring moving back and forth on a frictionless floor. d) A liquid column moving up and down a U-tube of uniform corss-sectional area about its equilibrium position of equal levels in each limb.
e) An electrical circuit having an inductance L across a capacitance C carrying a charge q.
So, mechanical as well as Electrical systems are now equivalent in their treatment.
A small displacement from its equilibrium position sets up a restoring force, this force is proportional and acts in such a direction towards the equilibrium position.
The equilibrium or rest position is equivalent to the mean position of a SHO
These observations are very vital to the understanding of the mechanism of S.H.M.
So, this restoring force is because of elasticity of the given medium. The disturbed system tries to recover and restore its original position after the deforming force is removed. The inertia of the medium comes into the picture now. Because of this property, the motion is repeated on either side of the mean position. In the absence of elasticity the recovery from the disturbed position of the given medium is not possible. And without inertia the undulations are not repeated. Thus we come on conclusion , that elasticity and inertia are two essential properties of a medium to sustain any harmonic wave motion.
Tuesday, January 4, 2011
SIMPLE HARMONIC MOTION IN PHYSICS
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Dear, before we take any detailed study of SIMPLE HARMONIC MOTION, let understand first the meaning of the word 'motion' and harmonicity or periodicity of a motion. So we see different objects around us, we generally call some of them moving, while others are at rest if an object does not change its position with the passage of that time, it is at rest. But if the position vector of a body changes with time, it is surely in the state of motion. Rest and motion, as all of us know are only relative concepts.
No object in this world can ever be in a absolute motion or at absolute rest. An object can have three types of motion :-
1 Translatory Motion- is the motion in which the object advances along a straight path, from point to point, as the time is elapsed or along a smooth curvillinear path.
2. Rotatory Motion - involves the motion of an object about a fixed point, often repeatedly covering the same path. Such a motion may be uniform or non-uniform.
3. Vibratory motion- is a motion, a body is found to move back and forth, on a given stretch of path, about a fixed point called its mean position.
While in case 1, the path is never repeated as the body advances, in cases 2 and 3 it is not so, The body repeats its motion on along the same fixed track. Typical eg. can be enumerated for each type of motion. For instance , a freely falling object an object sliding down an inclined plane, a train running over its track etc. are examples of translatory motion, Motion of our own earth around the sun, hands of a clock, an electron moving around an atomic nucleus, etc are typical eg. of rotatory motion. Motion of a clock pendulum, fluttering wings of a honey bee etc. are all eg. of vibratory motion.
No object in this world can ever be in a absolute motion or at absolute rest. An object can have three types of motion :-
1 Translatory Motion- is the motion in which the object advances along a straight path, from point to point, as the time is elapsed or along a smooth curvillinear path.
2. Rotatory Motion - involves the motion of an object about a fixed point, often repeatedly covering the same path. Such a motion may be uniform or non-uniform.
3. Vibratory motion- is a motion, a body is found to move back and forth, on a given stretch of path, about a fixed point called its mean position.
While in case 1, the path is never repeated as the body advances, in cases 2 and 3 it is not so, The body repeats its motion on along the same fixed track. Typical eg. can be enumerated for each type of motion. For instance , a freely falling object an object sliding down an inclined plane, a train running over its track etc. are examples of translatory motion, Motion of our own earth around the sun, hands of a clock, an electron moving around an atomic nucleus, etc are typical eg. of rotatory motion. Motion of a clock pendulum, fluttering wings of a honey bee etc. are all eg. of vibratory motion.
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