Input and Output Devices

Input and Output Devices

(Chapter-3)

Printer
A computer peripheral that puts text or a computer generated image on paper or on another medium, such as a transparency. Printer can be categorized in several ways the most common distinction is IMPACT and NON-IMPACT.


Impact Printing
Is the method used by the conventional type writers. In some type of impact printing a metal “hammer” embossed with a character strikes a print ribbon, which presses the characters image into paper. In other types the hammer strikes the paper and presses it into the ribbon characters created through impact printing can be formed by either a solid font or dot matrix printing mechanism.

Data Processing

Data Processing

(Chapter-2)

Data Processing
Data processing often referred as D.P is a process of collecting the data together and converting the data into information. The method used for collecting the data may be manual, mechanical or electronic.
Data processing is a term mostly associated with business and commercial work. Since computers are being used in the processing of data the term “electronic data processing” may also be used.


Electronic Data Processing
Data processing means transformation of data into more meaningful results for carrying out scientific, business activities. The result of data processing is called “information”. The transformation of data consist of a sequence of operations. The sequence is called “procedure”.
Input -> Processing -> Output

Introduction to Computers

Introduction to Computers

(Chapter-1)

Computer
A Computer is an automatic electronic, calculating device which can process a given input in a prescribed manner to produce a desired output, at a very high speed with remarkable accuracy. It can also perform all arithmetic and logical functions according to instructions given in a systematic order to solve any problem and produce processed information.


Advantages of Computers


Speed
Since Computer is an electronic machine and electrical pulses travel at the rate of passage of electric current. This speed enables the computer to perform millions of calculations per second.


Storage
A computer has too much storage capacity. Once recorded, a piece of information can never be forgotten.

Glossary

Acidity

The acidity of a base is defined as the number of ionizable hydroxyl groups in its molecule.


Anode
It is an electrode through which electrons enter the external circuit.


Alpha Rays
There are positively charged particles emitted from a radioactive substance. They carry two positive charges and are called helium nuclie.


Analytical Chemistry
It is the branch of chemistry which discusses the analytical methods forgetting information about chemical compounds and chemical processes.

Differences

Metals and Non Metals

Metals
1. Metals have luster shine surface.
2. Metals reflect heat and light.
3. Metals conduct heat and electricity
4. Metals are ductile and can be drawn into wire.


Non-Metals
1. Non-Metals have no luster.
2. Non-Metals usually don’t reflect heat and light.
3. Non-Metals do not conduct heat and electricity.
4. Non-Metals are non ductile and cannot be drawn into wire.
5. Non-Metals are non-malleable and can not form sheets.

Electro-Chemistry

Electro-Chemistry

(Chapter – 7)

Electro-Chemistry
The branch of chemistry which deals with the study of chemical energy to electrical energy or electrical energy to chemical energy is called electro-chemistry.


Conductors
Those substances through which electric current can pass are called conductors. For example all metals are conductors.


Non-Conductors
Those substances through which electric current cannot pass are called non-conductors. For example plastic, wood are non-conductors.

Solution and Suspension

Solution and Suspension

(Chapter-6)

Solution
A homogeneous mixture of different chemical substances which has uniform chemical composition through out and shows uniform physical properties is called solution. For example dissolve a small amount of copper sulphate in water the water will become blue. If this blue liquid is filtered, it will pass through the filter paper without leaving any solid. The mixture thus prepared is called a solution.


Binary Solution
A solution which is formed by mixing two substances is called binary solution. For example solution of glucose and water.

States of Matter

States of Matter

(Chapter-5)

States of Matter
Matter has three states:
1. Gas
2. Liquid
3. solid
These are physical states of matter. The three states of one matter may have different physical properties while their chemical properties are same. Water exists in three physical states solid (ice), liquid and gas(steam) has same chemical properties.

Periodicity of Elements & Periodic Table

Periodicity of Elements and Periodic Table

(Chapter – 4)

Definitions
Periodic Table
A table of elements obtained by arranging them in order of their increasing atomic number in which elements having similar properties are placed in the same group is called Periodic Table.


Group
The vertical column of elements in the periodic table are called Groups.


Period
The horizontal rows of elements in the periodic table are called Periods.


Periodicity
The repetition of physical and chemical properties of elements periodically is called Periodicity of Properties.

Atomic Structure

Atomic Structure

(Chapter-3)

Dalton’s Atomic Theory
The important postulates of Dalton’s atomic theory are:
1. All elements are composed of atoms. Atom is too small so that it could not be divided into further simpler components.
2. Atom cannot be destroyed or produced.
3. Atoms of an element are similar in all respects. They have same mass and properties.
4. Atoms of different elements combine in a definite simple ratio to produce compounds.


Discovery of Electron
A discharge tube is a glass tube. It has two electrode, a source of electric current and a vacuum pump.
(Diagram)
Sir William Crooks (1895 performed experiments by passing electric current through gas in the discharge tube at very low pressure. He observed that at 10-4 (-4 is power to 10) atmosphere pressure, shining rays are emitted from cathode. These rays were named cathode rays. Cathode rays are material particles as they have mass and momentum.

Chemical Combination & Chemical Equation

Chemical Combinations & Chemical Equation   
(Chapter-2)

Laws of Chemical Combinations
There are four laws of chemical combinations these laws explained the general feature of chemical change. These laws are:
1. Law of Conservation of Mass
2. Law of Definite Proportions
3. Law of Multiple Proportions
4. Law Reciprocal Proportions 


Antoine Lavoiser has rejected the worn out ideas about the changes that take place during a chemical reaction. He made careful quantitative measurements in chemical reactions and established that mass is neither created nor nor destroyed in a chemical change. 

Introduction to Chemistry

Introduction to Chemistry

(Chapter-1)

Chemistry
The branch of science which deals with the study of matter,its composition and structure, changes in matter and laws and principles which govern these changes.

Matter
Anything that has mass and occupies space is called matter.For example,gases,air and water etc.

Branches of Chemistry
Some main branches of chemistry are as follows: