LONG SIGHTEDNESS OR HYPER METROPIA

SYMPTOMS
In HYPER METROPIA, a person can not see objects clearly which are near to him, but he can see clearly     distant objects
REASON
The reason for HYPER METROPIA is that either the focal length of the lens of eye is too long or the     eyeball is too short.
WHAT HAPPENS IN HYPER METROPIA
In HYPER METROPIA, light rays from a near object are focused behind the Retina.
CORRECTION OF DEFECT
This defect can be corrected by using a convex lens of suitable focal length
POWER OF LENS
Power of lens is defined as the reciprocal of the focal length of the lens in meters.
FORMULA:
Power = 1/f(in meter)
Unit of power of lens is Dioptre.
DIOPTRE
Dioptre is defined as the power of lens whose focal length is one meter
if f =1 meter then the power of the lens = 1 dioptre.

STATICS

Statics
Statics is the branch of mechanics which deals with the study of bodies at rest under a number of    forces, the equilibrium, conditions of equilibrium, types of equilibrium and torque etc.
Equilibrium
A body is said to be in equilibrium if it is at rest or moving with uniform velocity.    In other words if the linear and angular acceleration of a body are zero, the body is said to be in    equilibrium.    Or we can say that when two or more forces act on a body such that their resultant or combining effect    on the body is Zero and the body retains its state of rest or of uniform motion then the body is said to    be in equilibrium.
Example
A book lying on the table, suspended bodies, all stationary bodies , jump by using parachute.
Types of equilibrium
With respect to the state of a body, equilibrium may be divided into two categories:    1. Static equilibrium.   2. Dynamic equilibrium.   For latest information , free computer courses and high impact notes visit :
Static equilibrium
If the combined effect of all the forces acting on a body is zero and the body is in the state of rest then    its equilibrium is termed asstatic equilibrium.   For example: All stationary bodies
Dynamic equilibrium
when a body is in state of uniform motion and the resultant of all the forces acting upon it is zero then it    is said to be in dynamic equilibrium.   For example: Jump by using parachute.
Conditions of equilibrium
There are two conditions of equilibrium are as follows
First condition of equilibrium
The first condition of equilibrium stated as follow:
To maintain the transitional equilibrium in a body the vector sum of all the forces acting on the body is    equal to zero    i.e.

MULTIPLICATION & DIVISION OF VECTOR BY A NUMBER (SCALAR)

MULTIPLICATION OF A VECTOR BY A SCALAR
When a vector is multiplied by a positive number (for example 2, 3 ,5, 60 unit etc.) or a scalar only its magnitude is changed but its direction remains the same as that of the original vector. If however a vector is multiplied by a negative number (for example -2, -3 ,-5, -60 unit etc.) or a scalar not only its magnitude is changed but its direction also reversed.
The product of a vector by a scalar quantity (m) follows the following rules:
	(m)  = (m) which is called commutative law of multiplication.
	m(n) = (mn) which is called associative law of multiplication .
	(m + n) = m+ n which is called distributive law of multiplication .
	DIVISION OF A VECTOR BY A SCALAR
	The division of a vector by a scalar number (n) involves the multiplication of the vector by the reciprocal of the number (n) which generates a new vector.
	Let n represents a number or scalar and m is its reciprocal then the new vector  is given by :
	where m = 1/n
	and its magnitude is given by:
	The direction of  is same as that of if (n) is a positive number.  The direction of  is opposite as that of if (n) is a negative number.

RESOLUTION OF VECTOR

DEFINITION
The process of splitting a vector into various parts or components is called "RESOLUTION OF VECTOR"
These parts of a vector may act in different directions and are called "components of vector".
	We can resolve a vector into a number of components .Generally there are three components of vector viz. Component along X-axis called x-component Component along Y-axis called Y-component Component along Z-axis called Z-component
	Here we will discuss only two components x-component & Y-component which are perpendicular to each other.These components are called rectangular components of vector.
	METHOD OF RESOLVING A VECTOR INTO RECTANGULAR COMPONENTS
	Consider a vector  acting at a point making an angle q with positive X-axis. Vector  is represented by a line OA.From point A draw a perpendicular AB on X-axis.Suppose OB and BA represents two vectors.Vector OA is parallel to X-axis and vector BA is parallel to Y-axis.Magnitude of these vectors are Vx and Vy respectively.By the method of head to tail we notice that the sum of these vectors is equal to vector.Thus Vx and Vy are the rectangular components of vector . Vx = Horizontal component of . Vy = Vertical component of .
	MAGNITUDE OF HORIZONTAL COMPONENT
	Consider right angled triangle DOAB
	MAGNITUDE OF VERTICAL COMPONENT
	Consider right angled triangle DOAB

Chemistry Notes and Review

Atomic and Molecular Structure

The building blocks of matter are atoms, which join together to form molecules or compounds. It's important to know the parts of an atom, what ions and isotopes are, and how atoms join together.

Parts of an Atom

Atoms are made up of three components:

• protons - positive electric charge
• neutrons - no electric charge
• electrons - negative electric charge

Protons and neutrons form the nucleus or center of each atom. Electrons orbit the nucleus. So, the nucleus of each atom has a net positive charge, while the outer portion of the atom has a net negative charge. In chemical reactions, atoms lose, gain, or share electrons. The nucleus does not participate in ordinary chemical reactions, although nuclear decay and nuclear reactions can cause changes in the atomic nucleus.

Atoms, Ions, and Isotopes

The number of protons in an atom determines which element it is. Each element has a one- or two-letter symbol that is used to identify it in chemical formulas and reactions. The symbol for helium is He. An atom with two protons is a helium atom regardless of how many neutrons or electrons it has. An atom may have the same number of protons, neutrons, and electrons or the number of neutrons and/or electron may differ from the number of protons.

Atoms that carry a net positive or negative electric charge are ions. For example, if a helium atom loses two electrons, it would have a net charge of +2, which would be written He2+.

Varying the number of neutrons in an atom determines which isotope of a element it is. Atoms may be written with nuclear symbols to identify their isotope, where the number of nucleons (protons plus neutrons) is listed above and to the left of an element symbol, with the number of protons listed below and to the left of the symbol. For example, three isotopes of hydrogen are:

11H, 21H, 31H

Since you know the number of protons never changes for an atom of an element, isotopes more commonly are written using the element symbol and the number of nucleons. For example, you could write H-1, H-2, and H-3 for the three isotopes of hydrogen or U-236 and U-238 for two common isotopes of uranium.

Atomic Number and Atomic Weight

The atomic number of an atom identifies its element and its number of protons. The atomic weight is the number of protons plus the number of neutrons in an element (because the mass of electrons is so small compared with that of protons and neutrons that it essentially doesn't count). The atomic weight sometimes is called atomic mass or the atomic mass number. The atomic number of helium is 2. The atomic weight of helium is 4. Note that the atomic mass of an element on the periodic table isn't a whole number. For example, the atomic mass of helium is given as 4.003 rather than 4. This is because the periodic table reflects the natural abundance of isotopes of an element. In chemistry calculations, you use the atomic mass given on the periodic table, assuming a sample of an element reflects the natural range of isotopes for that element.

Molecules

Atoms interact with each other, often forming chemical bonds with each other. When two or more atoms bond to each other, they form a molecule. A molecule can be simple, such as H2, or more complex, such as C6H12O6. The subscripts indicate the number of each type of atom in a molecule. The first example describes an molecule formed by two atoms of hydrogen. The second example describes a molecule formed by 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen. While you could write the atoms in any order, the convention is to write the positively charged past of a molecule first, followed by the negatively charged part of the molecule. So, sodium chloride is written NaCl and not ClNa.