HOW TO FILL ONLINE APPLICATION FORM
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Army Engineering For Boys
* Courses starting on July 2014
* Registration ending on 29th November 2013
Army engineering courses are for 5 years and could enter in a rank of left and officers. At least 70% mark required in the subjects Physics,chemistry and maths in +2. Going +2 students can apply this.Students those who are between 16.5 & 19.5 age could apply for this exam.
Selection
Eligible students are asked to face the five day service selection board interview.That is not only an interview, they check mental growth and each and every personality.All types of medical tests are required.
Advantages
After 3 year a stiff of RS 21000 per month will be rewarded.After the courses a job of salary RS 27000 and other privileges will be provided.Salary and service all together will award a person RS 65000.There are promotions based on your performance.
Registration
http://www.joinindianarmy.nic.in/ Apply online for TES 31 course.2 copy of application must be printed.Photo and signature must be printed on it.Attested 12th and 10th examination certificate (going 12th student only 10th examination certificate) must be keep.During the interview this must be taken along with you.
BORON FAMILY
//Here we are going to study more about boron family in p-block
These are the main elements in Boron family
-
B
Al
Ga
In
Tl
Now lets study more detailed about boron family.
*Boron is a well known metal and it always form covalent bonds. It has 5 electrons which revolve around nucleus. Its atomic number is 5.
Atomic size
There is always a increase in atomic size due to the increase in number of shells. But as an exception there is a small decrease in size of aluminium to gallium. This is observed due to the poor screening effect of 10 d electrons,and there is a considerable increase in size from In to Tl due to the poor screening effct of 14 f electrons.
Ionisation enthalpy
The Solid State
General Characteristics of Solid State
(i) They have definite mass, volume and shape.
(ii) Inter molecular distance are short
(iii) Inter molecular forces are strong
(iv) Their constituent particles (atoms, molecules or ions) have fixed positions and can only oscillate about their mean positions
(v) They are incompressible and rigid
Solids can be classified as crystalline or amorphous on the basis of the nature of order present in the arrangement of their constituent particles.
A regular three dimensional arrangement of points in space
Bravais Lattices
There are only 14 possible three dimensional lattices.These are called Bravais Lattices
Lattice Point or Lattice Site
Each point in a lattice is called Lattice Point or Lattice Site
(i) They have definite mass, volume and shape.
(ii) Inter molecular distance are short
(iii) Inter molecular forces are strong
(iv) Their constituent particles (atoms, molecules or ions) have fixed positions and can only oscillate about their mean positions
(v) They are incompressible and rigid
Solids can be classified as crystalline or amorphous on the basis of the nature of order present in the arrangement of their constituent particles.
Property
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Crystalline Solids
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Amorphous Solids
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Shape
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Definite characteristic geometrical shape.
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Irregular shape.
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Melting Point
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Melt at a sharp and characteristic temperature
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Nature |
True solids
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Glass, Rubber and plastics
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Classification of crystalline solids
1) Molecular solids
(i) Non polar :- Dispersion or London force | Ar , CCl4 , H2 , I2 , CO2
(ii) Polar :- Dipole-dipole interactions | HCl , SO2
(iii) Hydrogen bonded :- Hydrogen bonding | H2O (ice)
2) Ionic solids :- Coulombic or electrostatics | NaCl , MgO , ZnS , CaF2
3) Metallic solids :- Metallic bonding | Fe , Cu , Ag , Mg
4) Covalent or network solids :- Covalent bonding | SiO2(quartz) , SiC , C(diamond,graphite) ,Hard Insulators Very high AIN
1) Molecular solids
(i) Non polar :- Dispersion or London force | Ar , CCl4 , H2 , I2 , CO2
(ii) Polar :- Dipole-dipole interactions | HCl , SO2
(iii) Hydrogen bonded :- Hydrogen bonding | H2O (ice)
2) Ionic solids :- Coulombic or electrostatics | NaCl , MgO , ZnS , CaF2
3) Metallic solids :- Metallic bonding | Fe , Cu , Ag , Mg
4) Covalent or network solids :- Covalent bonding | SiO2(quartz) , SiC , C(diamond,graphite) ,Hard Insulators Very high AIN
Crystal Lattices
A regular three dimensional arrangement of points in space
Bravais Lattices
There are only 14 possible three dimensional lattices.These are called Bravais Lattices
Each point in a lattice is called Lattice Point or Lattice Site
Magnetic Effect of Current
Magnetic Effect of
Current
Magnetic Field
The space around a current carrying conductor in which
its magnetic effect can be experienced is called magnetic field.
Biot-Savart’s Law
The law states that “the magnetic field at any point
due to an element of a conductor carrying a current is
(i) Directly proportional to the strength of
current
(ii) Directly proportional to the length of the
element
(iii) Directly proportional to the sinθ , where 'θ' is the angle between
the element and the line joining the element to the point
(iv) Inversely proportional to the square of
distance between the element and the point
dB ∝ idlsinθ/r²
dB=(µo)/4π x idlsinθ/r²
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Unit: - Wb/m² or tesla
µo Is called permeability of
free space
µo = 4π x 10000000
Right hand Grip Rule
It states that “If conductor carrying current is held
in the right hand (grasped) such that the thumb points in the direction of the
current , then the direction of finger tips round the wire represents the
direction of the magnetic field lines.
Maxwell’s right handed screw rule
If a right handed cork screw is rotated so that its tip
moves in the direction of flow of current through the conductor, then the
rotation of the head of the screw gives the direction of magnetic lines of
force.
Right Hand Palm Rule
The rule states that “If the direction of the circular
current is represented by the direction of the closed fingers of the right
hand, then the stretched thumb will give the direction of the magnetic field”.
Ampere’s circuital Law
Theorem states that “the line integral of the magnetic
field (B) around any closed path in free space is equal to µo times the total current enclosed by the path.”
∫B x dl=µo(i net)
Remaining topics will be added soon
Short Notes on Electro Statics
Short Notes on Electro Statics
Number of
electrons = (Total
charge)/(Charge of one electron)
n=q/e
q=ne
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Coulomb’s Law
“It states that two point
charges repel or attract each other with a force which is directly proportional
to the product of the magnitude of the charges and inversely proportional to
the square of distance between them.”
F=1/4Πεο×q1q2/r²
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Linear
charge density:- λ=q/L
Surface
charge density:-
Volume
charge density:- ρ=q/V
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In Coulomb’s law the
charges if placed in another medium,
Then,
F medium
= F
air
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K = 1/4Πεο×1/K×q1q2/r²
Where K is called
dielectric constant of medium
E=F/q
F=qE
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Electric field due to a point charge
Consider a single point
charge ‘q’ , Let ‘r’ be the vector from q to a general point P where the test
charge qο is
placed.
By Coulomb’s law,
F=(1/4Πεο)x(qqο/r²)x r ^
E=q/qο
E=(1/4Πεο)x(q/r²)x r^
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The electric field vector
points radially outwards if q > 0 and radially inwards if q < 0.
Electric field inside a
conductor is zero.
Dipole moment
→ →
P = q(2a)
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Electric field on the axial line of an electric dipole
E=[1/4Πεο]×[(2Pr )/(r²-a²)²]
E=[1/4Πεο]×[(4qra )/(r²-a²)²]
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When a<<r
Then ,
E=[1/4Πεο]×[2P/r³]
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Electric
field on equatorial line
E=[1/4Πεο]×[P/(r²+a²)^3/2]
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When a<<r
Then ,
E=[1/4Πεο]×[P/r³]
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Torque of the dipole in the uniform electric field,
→ →
ζ=P × E
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Electric Flux
φ=∫E.ds
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