Current Affairs 6th Class

Magnetism

Learning Objectives 1. Introduction 2. Magnetic and Non-magnetic materials 3. Poles of a magnet 4. Directive properties of magnets 5. Types of magnets - Permanent, Temporary magnets – Electromagnets 6. Maglev 7. Loss of Magnetism INTRODUCTION Magnet was discovered about 4000 years ago. We observe that filings of some materials like iron, nickel, cobalt etc., cling to magnets, however other things around us like wood, plastic etc. are not affected by the presence of magnet near them. The name magnetite has been derived from magnesia and magnets are named after magnetite. You must have often observed that when a refrigerator door is opened a little and left, it shuts by itself. Also many cupboard doors also click shut the same way. It happens because they have magnets inside. Thus we can define magnets as the materials which attract certain substances (magnetic) like iron, cobalt, nickel etc. Do You Know The ancient greeks observed electric and magnetic phenomena as early as 700 B.C. They found that a piece of amber when rubbed attracts pieces of straw or feathers. MAGNETIC AND NON-MAGNETIC MATERIALS All objects are not attracted to magnets. When we bring a magnet near various objects, some are attracted to the magnet and some are not. The materials which get attracted to the magnets are called magnetic materials. Iron, Cobalt and Nickel are some examples of magnetic materials. On the other hand, the materials which are unaffected by magnets are called non-magnetic materials. Wood, plastic, gold, silver, cotton etc., are some examples of non-magnetic materials. Do You Know Magnets help in case of mental unrest by applying the south pole of a weak magnet to the forehead for about 10 minutes daily. POLES OF A MAGNET The magnetic forces are strongest at the two ends of a bar magnet. These ends are called the poles of a magnet. There are two poles of every magnet and they are termed as North Pole and South Pole It is important to note that the two poles cannot exist independently. Poles always exist in pairs. So if a magnet is cut into pieces, then even the smallest piece of a magnet will have both the poles.

Attraction and Repulsion It is observed that when the ends of two magnets are brought near each other, they either pull towards or push away from each other. The pulling of magnets towards each other is termed as attraction and pushing away from each other is called repulsion. When North pole of a magnet is brought near the more...

Catgeory: 6th Class

Natural Phenomena: Rain, Thunder and Lightning

Learning Objectives 1. Introduction 2. The three states of water 3. Clouds and Rain 4. Water cycle 5. Lightning and thunder INTRODUCTION A natural phenomenon is an event that occurs naturally. Natural phenomena cannot be controlled by humans but they affect the humans in many ways. Some of the natural phenomena are rain, lightning, thunder, earthquakes, storms etc. In this chapter we will learn about formation of clouds, rain, lightning and thunder. Do You Know Water which is fit for human consumption and can be used for agricultural purposes is just 2.6% of the total. THE THREE STATES OF WATER Water exists in three states viz solid (ice or snow), liquid (water) and gas (steam/water vapour). All the three states are observed in our everyday life. The three states of water are inter convertible. Ice changes to water through the process of melting, melting point of ice is 0°C. Also water at 0°C can change to ice and process is called freezing.

Three states of water and their inter conversion Similarly, water on heating to 100°C starts boiling and changes into steam. This process is called vaporisation or Boiling. Also steam or water vapour on cooling change to liquid water and the process is called condensation. You can see snow on mountains. Snow is a natural form of ice. Snow melts and the water flows down through the hills. We observe in our surroundings that water from sea, lakes, ponds, plants, etc. water evaporates all the time (especially in summer), and the evaporated water goes into the air as water vapour. A very common observation is formation of water droplets on a glass containing cold water or ice cubes. It happens because the water vapour present in the atmosphere changes (condenses) into water drops on coming in contact with the cool glass. .

Do You Know Antarctica is the driest continent on the earth. Rain on venues is made up of sulphuric acid and due to intense heat there, is evaporates before reaching the surface. CLOUDS AND RAIN The air around us is moist. It is because water keeps on evaporating from the water bodies such as lakes, rivers, sea etc. on the surface of earth. Though we cannot see the water vapours as they are invisible but we can always feel them. For e.g. on a hot and sticky day in summer, or on a cold foggy day of winters, we can feel the water vapours all around us. The warm air holding more...

Catgeory: 6th Class

Components of Food

Learning Objectives 1. There are 6 nutrients in our food; carbohydrates, fats, proteins, vitamins, minerals and water. 2. Deficiency of nutrients leads to deficiency diseases. 3. Fiber or roughage is also necessary for our digestive system. 4. A balanced diet is necessary to remain healthy. We take food every day, it is the basic necessity of life. Food provides usenergy to work, to grow and protects us from diseases. Proper food keeps us ingood health. The kind of food that we eat, depending on our liking and availability rawfood materials form our food habits. Some people eat wheat based mealswhereas some prefer rice based meals. Some take non-vegetarian food whileothers are vegetarians. However, in spite of the great diversity in the foodhabits of the people, we either consume food that are plant based or come fromanimals sources. FUNCTIONS OF FOOD

Energy giving food: These food items provide energy to our body to dowork. g. sugar, cereals, jiggery, oil fats, starchy vegetables (potato, sweet potato) etc.

Body building food: These food items are growth promoting. g. milk, pulses, meat, egg, fish etc.

Protective food: Food items that protect our body against diseases fallunder this category. E.g. vitamins and minerals present in milk, greenleafy vegetables and fruits.

COMPONENTS OF FOOD The main components of foods are carbohydrates, protein, fats, vitamins andminerals. These are called nutrients. Carbohydrates Carbohydrates are also called energy giving food. It is the main sources of energy It is made up of carbon, hydrogen, and oxygen. There are three types of carbohydrates. (a) Sugars: It is a simple carbohydrate having sweet taste. Sources of sugarare glucose, Sugarcane, milk and fruits; such as banana, apple, grapes, etc.

(b) Starch: It is a complex carbohydrate. It is a tasteless, colour less, white power. Sources of starch are : wheat, maize, potato and rice. (c) Cellulose: It is present in plant cell wall. It is a complex carbohydrate. Humans cannot digest cellulose. Children, players and people who do manual work require more carbohydrates. Protein

Protein helps in body growth and repairs the tissues so it is also called bodybuilding food. We get protein from milk, eggs, meat, fish and all kinds ofpulse. Protein molecule is made of a large number of smaller molecules called aminoacid. The daily requirement of protein for adults is 1 gram per kilogram of thebody weight. When the body is building new tissue, more proteins are required, so growing children and pregnant lady more...

Catgeory: 6th Class

Air Around Us

Learning Objectives 1. Air is a natural resource 2. We cannot see air but can feel it 3. Role of atmosphere 4. Oxygen cycle 5. Composition of air 6. Usefulness of air 7. Pollution of air Air is also an important natural resource. Air is present everywhere, in water, around us, in soil and within plants and animals. Life on Earth is not possible without air. Air cannot be seen lent it can be felt. When air blows hard, leaves and branches start moving. This movement signifies presence of air. Strong moving air is called wind and strong winds cause storms. Presence of Air: We can feel air when we switch on a fan. We feel the cool breeze (air). Atmosphere: The thin layer of air surrounding the Earth is called the atmosphere. All plants and animals need air to breathe.

Air Balloons Properties of air \[\to \]Air occupies space. \[\to \]Air exerts pressure. \[\to \]Air cannot be seen but it can be experienced. The atmosphere extends upto 1000 km above the surface of Earth. However this air gets thinner and thinner as we go up. That is why mountaineers have to carry their own oxygen supply in oxygen in cylinders. Ninety nine percent of air is found up to a height of 30 km above the surface of Earth. Composition of air Air is a mixture of gases, water vapour and dust particles. Lavoisier was the first scientist to prove that air is a mixture of gases and not a compound. He found that (1) Air is a mixture of gases. Oxygen is the active part of air and make up about one fifth of air by volume. (2) When certain substances are burnt in air, they combine with oxygen. So air is a mixture and not a compound.

Composition of dry air. Dry air is without water vapour

Gas	Percentage by volume
1. Nitrogen 2. Oxygen 3. Rare gases (including 0.93% argon and0.018% neon) 4. Carbon dioxide 5. Impurities	78.09 20.95 01.00 0.02 to 0.04 Variable

Interesting Fact: Until the 18th century, people thought that air uses a single substance. In 1774, Joseph Priestly showed that more...

Catgeory: 6th Class

MENSURATION

Learning Objective

To understand the concept of Area and Perimeter of plane figures (triangle, rectangle and square).
To learn how to calculate area and perimeter of triangle, react angel and square.
To understand how to calculate area and circumference of circle.
To learn how to calculate surace area and volume of solid figures (cube and cuboid).

AREA AND PERIMETER OF PLANE FIGURE PERIMETER The perimeter of a plane geometrical figure is the total length of sides (or boundary) enclosing the figure. Units of measuring perimeter can be mm, cm, m, km etc. AREA The area of any figure is the amount of surface enclosed within its bounding lines. Area is always expressed in square units. 1. TRIANGLE Perimeter of a triangle is equal to the sum of its sides. For a triangle having sides a, b and c, Perimeter \[=a+b+c\] and area \[(A)\,=\sqrt{s(s-a)(s-b)\,(s-c)}\] where \[s=\frac{a+b+c}{2}\] area of equilateral triangle with each side a is \[\frac{\sqrt{3}}{4}{{\text{(side)}}^{2}}\]. Observe the given figure Area of \[\Delta ABC\]\[=\frac{1}{2}\times base\times height\]

\[=\frac{1}{2}\times BC\times AD\] Observe the given figure, \[\Delta \,ABC\] is a right angled triangle, right angled at B.

Area of \[\Delta \,ABC=\frac{1}{2}\,BC\times AB\] For Example: Find the perimeter and area of triangle ABC. Sol: \[P=AB+BC+CA\] = 7 + 4 + 5 = 16 cm Base = BC, Height =AD

Area \[=\frac{1}{2}\times BC\times AD\] \[=\frac{1}{2}\times 4\times 3\] \[=6c{{m}^{2}}\] 2. RECTANGLE Area of rectangle \[ABCD=AB\times BC=l\times b\] Perimeter of rectangle = sum of all sides \[=l+b+l+b\] \[=2l+2b\] \[=2(l+b)\]

Diagonal (AC) of rectangle \[=\sqrt{{{l}^{2}}+{{b}^{2}}}\] For example:

For the adjoining rectangle find: (i) the perimeter; (ii) the area. Sol. Perimeter \[=2(l+b)\,=2(6+4)\,=2\times 10=20\,cm\] Area \[=l\times b=6\times 4=24\,c{{m}^{2}}\] 3. SQUARE

Perimeter of square ABCD with side \[a=4a\] Area of square with side \[a={{a}^{2}}\] Diagonal of square more...

Catgeory: 6th Class

ALGEBRA

Learning Objective

To understand algebraic expression, variables, constants, like and unlike terms, coefficient of term.
To understand types of algebraic expression (Monomial, binomial trinonial and polynomials)
To learn about the algebraic equation and how to solve it.
To learn how to add, subtract and multiply and divide the polynomials.

The branch of mathematics which deals with numbers is called Arithmetic. Algebra can be considered as generalization of arithmetic, where we use letters in place of numbers, which allows to write rules and form in general way VARIABLE A symbol which takes various numerical values is called a variable. CONSTANT A symbol which takes a fixed numerical value is called a constant. ALGEBRAIC EXPRESSIONS When variables and constants are combined with the help of mathematical operations of addition, subtraction, multiplication and division, we get an algebraic expression. For example, 3x + 7, 15y - 23 are algebraic expression. 3x+7 is an algebraic expression in variable x, it is obtained by multiplying the variable x by constant 3 and then adding 7 to the product. TERMS Look at the expression (3x + 7). This is formed by first forming 3x as product of 3 and x and then adding 7 to the product. Similarly \[(10{{x}^{2}}+15)\] can be formed by first forming \[10{{x}^{2}}\] as product of 10, x and x and adding 15 to it. Such parts of an expression which are formed first and then added are called terms. Consider \[(9{{y}^{2}}-8x),\] here we can say that \[9{{y}^{2}}\] and - 8x are two terms of given expressions. FACTORS OF A TERM Now we know that an expression consist of terms. \[(9{{y}^{2}}-8x)\] has two terms \[9{{y}^{2}}\] and (-8x). The term \[9{{y}^{2}}\] is a product of 9, y and y. Here we say that 9, y and y are factors of term\[9{{y}^{2}}\]. A term is represented as product of its factors. For term (-8.x), -8 and x are factors. COEFFICIENTS OF A TERM We know that any term of an expression can be expressed as product of its factors. These factors are numeric or variables. The numerical factor is called numerical coefficient or coefficient of the term. In \[9{{y}^{2}}\], 9 is the coefficient of the term. It is also called coefficient ofy2. In - lO^z2, -10 is the coefficient of \[{{y}^{2}}{{z}^{2}}\]. If the coefficient of any term is + 1, we omit it. \[1{{y}^{2}}\] can be written as y2, 1xy is written as xy coefficient (-1) is indicated by minus (-) sign, \[(-1){{y}^{2}}\] is written as \[-{{y}^{2}},\,(-1)\,{{y}^{2}}{{z}^{2}}\] as \[-{{y}^{2}}-{{z}^{2}}\] etc. as -y2, (-1) more...

Catgeory: 6th Class

NUMBER SYSTEM

Learning Objective

To know about the types of Numbers.
(Natual numbers whole numbers. even. odd, prime, composite.co-prime, twin primes. perfect numbers, integers etc.)
To understand the divisibility of whole numbers.
To learn how to round off a number nearest to ten, hundred and thousand.
To know how to compare numbers.
To learn how to calculate factors, multiples, prime factors H.C.F. (highest common factor) and L.C.M (lowest common factor) of numbers
To understand the representation of integers (positive and negative) on number line.
To learn the order of integers, absolute value of integer.
To team how to add and subtract integers with and without number line.
To learn BODMAS rule and uses of brackets.

NATURAL NUMBERS (i) Counting numbers 1,2,3,4, 5, ....are called Natural numbers. (ii) The set of natural numbers is denoted by N i.e., N = {1, 2, 3, 4, 5,.........} (iii) 1 is the smallest natural number. (iv) There is no largest natural number, i.e. the set of natural numbers is infinite. (v) Any natural number can be obtained by adding ' 1' to its previous natural number. WHOLE NUMBERS (i) All natural numbers together with zero are called whole numbers, as 0, 1, 2, 3, 4,... are whole numbers. (ii) The set of whole numbers is denoted by W, i.e. W = {0, 1, 2, 3, 4, 5.....} (iii) \[W=N\cup \{0\},\] where N is the set of natural numbers. (iv) 0 is the smallest whole number. (v) There is no largest whole number i.e. the number of the elements in the set of whole numbers is infinite. (vi) Every natural number is a whole number. i.e. \[N\subseteq W\] i.e. N is a subset of W. (vii) 0 is a whole number, but not a natural \[0\in W\] but \[0\notin N\] EVEN NUMBERS (i) Whole numbers which are exactly divisible by 2 are called even numbers. (ii) The set of even numbers is denoted by 'E', such that E= {0, 2, 4, 6, 8.....}. (iii) The set E is an infinite set. ODD NUMBERS (i) Natural numbers which are not exactly divisible by 2 are called odd numbers. (ii) The set of odd numbers is denoted by '0' such that O = { 1, 3, 5, 7, 9.....} (iii) The set 0 is an infinite set. PRIME NUMBERS (i) Natural numbers having exact two distinct factors i.e., 1 and the number itself are called prime numbers. more...

Catgeory: 6th Class

ARITHMETIC

Learning Objective

To understand the term fraction and its types (proper, improper mixed, equivalent, like and unlike fractions)
To learn how to odd. Subtract multiply and divide proper, improper and mixed factions.
To understand the term decimal and representation of decimals on number line.
To learn how to compare decimal.
To learn how to add, subtract multiply and divide decimals.
To understand the terms ratio and proportion.
To learn how to find the value of one unit by using unitary method.

FRACTION Fraction is a method for representing the parts of a whole number. In the fraction, \[\frac{a}{b},\] a is the numerator and b is the denominator. Example: \[\frac{2}{3},\,\frac{7}{8},\,\frac{3}{7},\,\frac{4}{9}]\ etc. TYPES OF FRACTION PROPER FRACTIONS In a proper fraction, the numerator is always smaller than the denominator. For example: \[\frac{1}{4},\,\frac{3}{5}\] etc. IMPROPER FRACTIONS In an improper fraction the numerator is greater than the denominator. For example: \[\frac{5}{3},\,\frac{7}{4}\] is

Fractions in the form of \[1\frac{1}{4}\] or \[2\frac{1}{2}\] are know as mixed fractions. Let us represent mixed fraction by using figures.

EQUIVALENT FRACTIONS Equivalent fractions represent same part of the whole. For example \[\frac{1}{2}\,=\frac{2}{4}\,=\frac{3}{6}\,=\frac{4}{8}\,=\frac{5}{10}\] We can find more equivalent fractions by multiplying or dividing the numerator and the denominator by the same number. SIMPLEST FORM OF A FRACTION A fraction is said to be in the simplest form (or lowest form) if its numerator and denominator have no common factor except 1. The easiest way to find the simplest form of a fraction is to divide the numerator and denominator by their HCF. For example: To reduce \[\frac{125}{225},\] find their HCF. HCF of 125 and 225 =25 \[\therefore \,\,\,\,\,\,\frac{125}{225}\div \frac{25}{25}=\frac{5}{9}\] simplest form To reduce \[\frac{36}{72}\] H.C.F of 36 and 72 = 36 \[\therefore \,\,\,\,\,\frac{36}{72}\div \frac{36}{36}=\frac{1}{2}\] simplest form. LIKE FRACTIONS Fractions with the same denominator are called like fractions. \[\frac{4}{13},\,\frac{3}{13},\,\frac{12}{13},\,\frac{9}{13}\] are examples of like fractions. UNLIKE FRACTIONS Fractions like \[\frac{1}{5},\,\frac{2}{3},\,\frac{3}{4}\] have different denominators are called unlike fractions. Fraction on the number line Let us draw a number line and mark \[\frac{3}{4}\] on it. \[\frac{3}{4}\] is greater than 0 and less that 1. As \[\frac{3}{4}\] means 3 part out of 4, we will divide the gap between 0 and 1 into four equal parts, and mark \[\frac{1}{4},\,\frac{2}{4},\,\frac{3}{4},\,\frac{4}{4}(=1)\] as shown below. more...

Catgeory: 6th Class

GEOMETRY

Learning Objective

To understand the terms point, line, line segment, interesting, lines. Parallel lines, concurrent lines, perpendicular lines, Transversal etc.
To understand angle, its types and their construction.
To understand triangles and its types based on the measurement of sides and magnitude of angles.
To understated Quadrilateral and types of quadrilateral (parallelogram, Rectangle, Rhombus Square, Trapezium etc.)
To know about a circle, parts of circle and its construction.
To know about polygons and its types (prism, pyramids etc.)
To understand the concepts of symmetry (line symmetry, reflection etc.)

POINT A point determines a location. A point has no dimensions i.e. no shape or size. For example: (i) The sharpened end of a pencil. (ii) Tip of a needle. LINE A line is a straight path that extends indefinitely in both directions. It has no end points. For example: The line is named as \[\overleftrightarrow{AB}\] and read as line AB.

LINE SEGMENT A line segment is a portion of a line with two fixed end points. For example: (i) An edge of a box. (ii)

This is a line segment named as AB and read as line segment AB. INTERSECTING LINES If two or more lines meet each other at one point then they are called intersecting lines.

AB and CD are intersecting lines and 0 is the point of intersection PARALLEL LINES If two or more lines do not meet each other, whenever they are extended, then they are called parallel lines.

AB is parallel to CD CONCURRENT LINES If three or more lines pass through a point, then they are called concurrent lines and the point through which these all lines pass is called point of concurrent.

TRANSVERSAL A line which intersects two or more given lines at distinct points is called a transversal of the given lines. For example

Here line \['\ell '\] is transversal of lines 'm' and 'n' PERPENDICULAR LINES Perpendicular lines are two lines that intersect each other at a right angle. For example:

A line AB placed horizontally and line CD placed vertically to AB as shown in above figure. ANGLES Two rays with a common initial point form an angle. The space within the arms of an angle, produced indefinitely, is called the interior of the angle. The space outside the arms of an angle, produced indefinitely, is called the exterior of the angle. Two angles which have a common arm, a common vertex, and lie on either side of the common arm are called adjacent angles. Here \[\angle \,AOB\] and \[\angle \,BOC\] are adjacent angles.

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Catgeory: 6th Class

TIME AND WORK

Learning Objective To learn about time taken to complete a work. To find number of person required to complete a given piece of work. TIME AND WORK If a does a work in ‘a’ days then in 1 day A does \[\frac{1}{a}\] of the work. If B does a work in 'b' days then in 1 day B does \[\frac{1}{b}\] of the work. Then in 1 day, if A and B work together, their combined work is \[\frac{1}{a}+\frac{1}{b}\,\text{or}\,\frac{a+b}{ab}\] The work will be completed when 1 unit of work is completed. Now using Unitary Method Time required to complete \[\frac{a+b}{ab}\] work = 1 day \[\therefore \] Time required to complete 1 work \[=\frac{1}{\frac{a+b}{ab}}\,=\frac{ab}{a+b}\] Here we should recollect our knowledge of variation. For example: A and B can do a piece of work in 20 days and 30 days respectively They work together and A leaves 5 days before the work is finished. B finishes the remaining work alone. In how many days is the total work finished? Solution. Let the work is completed in 'f days. A works for (t - 5) days and B works for 't' days. Now A's work + B's work = 1 \[\therefore \]\[\frac{t-5}{20}+\frac{t}{30}\,=1\,\,\Rightarrow \,\,3t-15+2t\,=60\,\Rightarrow \,5t=60+15\] \[\Rightarrow \,\,5t+75\,\,\Rightarrow \,\,t=15\] days. \[\therefore \] Time required to finish the work is 15 days.

Catgeory: 6th Class

Current Affairs 6th Class

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