12th Class

  International Trade   You have already studied about the various aspects of International trade in the book Fundamentals of Human Geography. International Trade is mutually beneficial as no country is self-sufficient. India’s International trade has undergone a sea change in recent years in terms of volume, composition as well as direction. Although India’s contribution in the world trade is as low as one per cent of the total volume, yet it plays a significant role in the world economy.   Let us examine the changing pattern of India’s International trade. In 1950-51, India’s external trade was worth Rs. 1,2140 million, which rose to Rs. 8,37, 1330 million in 2004 - 05. Can you calculate the percentage growth in 2004-2005 over 1950-51? There are numerous reasons for this sharp rise in overseas trade, such as, the momentum picked up by the manufacturing sectors, the more...

  Geographical Perspective on Selected Issues and Problems   Environmental Pollution Environmental pollution results from ‘the release of substances and energy from waste products of human activities. There are many types of pollution. They are classified on the basis of medium through which pollutants are transported and diffused. Pollution can be classified into (i) air pollution, (ii) water pollution, (iii) land pollution and (iv) noise pollution.   Water Pollution Indiscriminate use of water by increasing population and industrial expansion has led degradation of the quality of water considerably. Surface water available from rivers, canals, lakes, etc. is never pure. It contains small quantities of suspended particles, organic and inorganic substances. When concentration of these substances increases, the water becomes polluted, and hence becomes unfit for use. In such a situation, the self-purifying capacity of water is unable to purify the water.   more...

  Human Geography Nature and Scope       You have already studied ‘Geography as a Discipline’ in Chapter I of the book, Fundamentals of Physical Geography (NCERT, 2006). Do you recall the contents? This chapter has broadly covered and introduced you to the nature of geography. You are also acquainted with the important branches that sprout from the body of geography. If you re-read the chapter you will be able to recall the link of human geography with the mother discipline i.e. geography. As you know geography as a field of study is integrative, empirical, and practical. Thus, the reach of geography is extensive and each and every event or phenomenon which varies over space and time can be studied geographically. How do you see the earth’s more...

  The World Population (Distribution, Density and Growth)   The people of a country are its real wealth. It is they who make use of the country’s resources and decide its policies. Ultimately a country is known by its people.   It is important to know how many women and men a country has, how many children are born each year, how many people die and how? Whether they live in cities or villages, can they read or write and what work do they do? These are what you will study about in this unit.   The world at the beginning of 21st century recorded the presence of over 6 billion population. We shall discuss the patterns of their distribution and density here.   Why do people prefer to live in certain regions and not in others?   The population of the world is more...

  Population Composition   People of any country are diverse in many respects. Each person is unique in her/his own way. People can be distinguished by their age, sex and their place of residence. Some of the other distinguishing attributes of the population are occupation, education and life expectancy.   SEX COMPOSITION The number of women and men in a country is an important demographic characteristic. The ratio between the number of women and men in the population is called the Sex Ratio. In some countries it is calculated by using the formula:   \[\frac{Male\,\,Population}{Female\,\,Population}\times 1000\] or the number of males per thousand females.   In India, the sex ratio is worked out using the formula:   \[\frac{Female\,\,Population}{Male\,\,Population}\times 1000\] or the number of females per thousand males.   The sex ratio is an important information about the status of women in a more...

  Human Development   The words ‘growth’ and ‘development’ are not new to you. Look around you, almost everything that you can see (and many that you cannot) grows and develops. These may be plants, cities, ideas, nations, relationships or even you yourself! What does this mean?   Do growth and development mean the same thing? Do they accompany each other?   This chapter discusses the concept of human development as it pertains to nations and communities.   GROWTH AND DEVELOPMENT Both growth and development refer to changes over a period of time. The difference is that growth is quantitative and value neutral. It may have a positive or a negative sign. This means that the change may be either positive (showing an increase) or negative (indicating a decrease).   Development means a qualitative change which is always value positive. This means more...

  Primary Activities   Human activities which generate income are known as economic activities. Economic activities are broadly grouped into primary, secondary, tertiary and quaternary activities. Primary activities are directly dependent on environment as these refer to utilisation of earth’s resources such as land, water, vegetation, building materials and minerals. It, thus includes, hunting and gathering, pastoral activities, fishing, forestry, agriculture, and mining and quarrying.   Why inhabitants of coastal and plain regions are engaged in fishing and agriculture respectively? What are the physical and social factors which affect the type of primary activities in different regions?   People engaged in primary activities are called redcollar workers due to the outdoor nature of their work.   HUNTING AND GATHERING The earliest human beings depended on their immediate environment for their sustenance. They subsisted on: (a) animals which they hunted; and (b) the more...

  Secondary Activities   All economic activities namely primary, secondary, tertiary and quaternary, revolve around obtaining and utilising resources necessary for survival.   Secondary activities add value to natural resources by transforming raw materials into valuable products. Cotton in the boll has limited use but after it is transformed into yarn, becomes more valuable and can be used for making clothes. Iron ore, cannot be used; directly from the mines, but after being converted into steel it gets its value and can be used for making many valuable machines, tools, etc. The same is true of most of the materials from the farm, forest, mine and the sea. Secondary activities, therefore, are concerned with manufacturing, processing and construction (infrastructure) industries.   MANUFACTURING Manufacturing involves a full array of production from handicrafts to moulding iron and steel and stamping out plastic toys to more...

                                                                                        Relations and Functions  

• To understand relations and functions let's consider two sets A = {1, 2, 3, 4} and B ={2,3}

Now, \[~A\times B=\{1,\,2,\,3,\,4,\}\times \{2,3\}=\{(1,\,2),\,(2,\,2),\,(3,\,2),\,(4,\,2),\,(1,\,3),\,(2,\,3),\,(3,\,3),\,(4,\,3)\}\] Let we choose an arbitrary set: R = [(1, 2), (2, 2), (1, 3), (4, 3)] Then R is said to be the relation between a set A to B.  

• Definition: Relation R is the subset of the Cartesian product\[A\times B\]. It is represented as

\[R=\{(x,\,y):x\in A\,\,\,and\,\,\,y\in B\}\] Note: the 2nd element in the ordered pair (x, y) is the image of 1st element Sometime, it is said that a relation on the set A means the all members / elements of the relation R be the elements / members of\[A\times A\]. Solved Example

Let \[A=\{1,\,2,\,3\}\] and a relation R is defined as \[R=\{(x,\,y):x<y\,\,where\,\,x,\,\,y\in A\}\]

Sol. more...

                                                                                         Matrices and Determinants  

• In previous classes, we have learnt the methods to solve linear equations. Let us consider the linear equations

\[{{a}_{1}}x+{{b}_{1}}y={{c}_{1}}\]                        (i) \[{{a}_{2}}x+{{b}_{2}}y={{c}_{2}}\]                        (ii) We have one of the methods to solve these equation by cross multiplication method. \[\frac{x}{{{b}_{1}}{{c}_{2}}-{{b}_{2}}{{c}_{1}}}=\frac{y}{{{c}_{1}}{{a}_{2}}-{{c}_{2}}{{a}_{1}}}=\frac{1}{{{a}_{1}}{{b}_{2}}-{{a}_{2}}{{b}_{1}}}\] Now, we learn to solve such equations with the help of matrices and determinants.  

• Matrix: A matrix is a rectangular array of numbers or expressions arranged in rows and columns. It is the shorthand of mathematics. It is an operator as addition, multiplication etc. Every matrix has come into existence through the solution of linear equations.

Given linear equation can be solved by matrix method & it is written as, AX = B Where    

• Definition: It is the more...