Current Affairs 10th Class

NCERT Summary - Energy

Energy MEANING OF ENERGY

When an object is capable of doing work, we say that it has energy. This means energy is the ability to do work.

HUMAN AND ENERGY

The most common form of energy humans have used over the ages and still continue to use is the energy stored in the muscles of the body. We obtain this energy from the food we eat. Of course, as we age or fall sick, our ability to do physical work decreases.
The external sources of energy used by humans in the seventeenth century were:
Fire: Primitive humans had discovered fire and used it for heat and light.
Food: The energy that the humans obtained from the food they ate was used to do most of their work.
Animals: Humans domesticated animals and used the energy of their muscles to perform more laborious tasks.
Wind and water: The kinetic energy of wind and flowing water was also used to do work through windmills and water wheels like grinding the grain, pottery, mining and metallurgy.

ACCOUNTING ENERGY

Whenever we move an object by the application of a force, we do some work. Work is measured in joules. When a force of one newton displaces an object by one metre, we say that one joule of work has been done. That is, all forms of energy are always measured in joules.

ACCOUNTING POWER

The rate at which energy is supplied is called power.

\[Power=\frac{Energy\,\,Supplied}{Time\,\,Taken}\]

If one joule of energy is supplied in a second, the power of the source is said to be one watt.

\[1\,\,Watt\,=\,\frac{1\,\,Joule}{1\,\,Seconed}\]

Power was earlier measured in a unit called horse power. One horse power was roughly equal to 746 watts.

\[1\,\,Horse\,\,Power\,=\,\,746\,\,watts\]

The kilowatt-hour is used as a commercial unit of energy.

SOLAR HEATING DEVICES

All solar heating devices are designed to facilitate the collection of as much solar energy as possible. Solar cooker and solar cell are chief examples of such kinds of device.

Solar Cooker

For making a solar cooker, a blackened sheet is placed in an insulated box and its open face is covered with a glass sheet.
The glass sheet on the top allows both visible and infrared components of the sunlight to fall on the blackened sheet. Often the inner walls of the box are also painted black to maximise absorption of heat and to minimise heat loss due to reflection.
When such a solar heating device is kept in the Sun for some time, its inner surfaces become hot after absorbing solar energy. As a result, these surfaces start radiating heat in the form of infrared radiations. However, the glass sheet on the top does not allow these radiations to go out. Thus, the heat inside more...

Catgeory: 10th Class

NCERT Summary - Fuels

Fuels

Substances that produce heat on combustion are called fuels.

DIFFERENT FORMS OF FUEL There are different forms of fuels:

Biomass fuel: The material contained in the bodies of plants and animals is called biomass. When organisms die, their biomass can be used as fuel for domestic purposes.
Agricultural wastes: Bagasse (sugarcane from which juice has been extracted) is sometimes burned in industrial boilers.
Wood: We bum wood in traditional chulhas.
Dung cakes: Animal dung in the form of dried cakes is also burned in many parts of the country for domestic purposes.
Biogas: It is unadvisable to bum dung cakes directly because animal dung contains vital nutrients should be returned to the soil. As duns cakes bum inefficiently and produce a lot of smoke, their utilisation as fuel leads to a considerable wastage of useful elements and causes air pollution. Instead, animal dung should be converted into biogas, which is a cleaner fuel. The residue, which is rich in nutrients, can then be used as manure.

Animal and plant wastes are easily degraded by anaerobic microorganisms in the presence of water. In this process, gases such as methane, carbon dioxide, hydrogen sulphide are produced. This mixture of gases is called biogas. It contains about 65 per cent methane, which is an excellent fuel. Biogas can be burned in gas stoves to produce heat. It can also be used for street lighting and for running engines.

Fossil fuels: Fossil fuels are formed over millions of years by the burial of plant and animal remains.

The most commonly used fossil fuels are: (i) coal (ii) petroleum (iii) natural gas. (i) Coal

Coal deposits are the distilled remains of large land plants which flourished in vast shallow swamps about 300 million years ago.
In India, coal is mainly found in Bihar, Orissa, Madhya Pradesh and West Bengal.
It consists largely of atoms of carbon, hydrogen, and oxygen, and a small amount of sulphur.
It comes in three main varieties—lignite, bituminous and anthracite.
Coal, when heated in the absence of air, gives coke. Coal tar and coal gas can be obtained from coal by a simple process known as destructive distillation.
Coal tar is a mixture of many carbon compounds. For about a hundred years, it was the chief source of important carbon compounds used in dyes, explosives, paints, synthetic fibre, drugs and pesticides.
Coal gas is a mixture of hydrogen, methane and carbon monoxide. This mixture is an excellent fuel. It was used for lighting homes, factories and streets.

(ii) Petroleum

Petroleum is formed by decomposition of microorganisms and dead organic matter. The dead organic remains sinks to the bottom and are gradually covered by sand and clay. Over millions of years, these remains are gradually transformed into hydrocarbons by heat, pressure and catalytic action. These hydrocarbons rise through the permeable rock layers. They form more...

Catgeory: 10th Class

NCERT Summary - The Sun and Nuclear Energy

The Sun and Nuclear Energy The Sun and Nuclear Energy

The Sun is the most direct and bountiful source of energy. It powers the flow of wind and water cycles on the Earth's surface and sustains all life.
Plants use this energy to make their food by the process of photosynthesis. It is this food that provides sustenance to humans and other animals on the Earth.
On studying the wavelength of light emitted by the Sun, it was concluded that it is largely made up of hydrogen. Hydrogen bums in the presence of oxygen and this process is called combustion. But combustion could hardly account for the massive amount of energy that we continue to receive from the Sun.
In 1939 German physicist, Hans Bethe gave correct explanation for the massive energy of the Sun. He proposed that the Sun contains in its core hydrogen nuclei moving at very great speeds. Whenever these lighter nuclei fuse to form the nucleus of a heavier element, a large amount of energy is liberated. It is this energy which we receive when the Earth faces the Sun.
Every square metre of the Earth's upper atmosphere receives 1.36 kJ of energy per second. However, all of this energy does not the surface of the Earth. Some of the light energy is reflected into space and some is absorbed by water vapour, ozone, dust and carbon dioxide present in the atmosphere. In fact, only 47 per cent of the energy that strikes the Earth's atmosphere reaches its surface and is absorbed.
To understand the source of the Sun's energy, we must understand the structure of atom. The atom consists of a positively charged heavy nucleus.
The nucleus consists of positively charged protons and neutral neutrons and negatively charged light electrons revolving around the nucleus.
The mass of one proton is approximately equal to the mass of 1836 electrons.
Although two atoms of an element always have the same number of protons, they can have different numbers of neutrons in their nucleus. For example, an atom of an element uranium always has 92 protons in its nucleus and 92 electrons orbiting around it. However, not all uranium atoms have the same number of neutrons in the nucleus. Some uranium atoms have 146 neutrons, while others have 143 neutrons. These two forms of uranium are called isotopes of uranium.
Each isotope is designated by the total number of protons and neutrons (nucleons) in its nucleus. This number (number of protons + number of neutrons) is called the mass number (Z) of the atom. Thus, a uranium atom with 146 neutrons is designated as \[U-238\,\,\left( 238=92+146 \right),\]while a uranium atom with 143 neutrons is designated as \[U-235\,\,\left( 235=92+143 \right).\]
The chemical symbol for uranium is U.
Most of the uranium found on the Earth is of more...

Catgeory: 10th Class

NCERT Summary - Nutrition

Nutrition Nutrition

We need food to live that is to carry on with our life processes. Food provides energy, helps in repairing damaged parts of cells and tissues, and makes materials necessary for growth and reproduction.

ENERGY REQUIREMENTS OF THE BODY

To be healthy and energetic, we need to consume nutritious food. Our food should be such that it takes care of our daily energy needs.
The requirement for energy varies with age and occupation. Growing children need more energy; so do pregnant women and nursing mothers. Other examples related to energy requirements are as follows:

Age Group	Energy Requirement (kilojoules)
5 years	6000
11 years	9000
18 years	11,000
Adult	9,600
Adult (heavy work)	12,000
Adult (very heavy work)	16,000

BALANCED DIET

The major components of food are carbohydrates, proteins, fats, vitamins and minerals. These are called nutrients. Besides these, water is an important constituent of our food, and makes up for two-thirds of our body weight.
A diet is balanced if it contains all the above mentions nutrients in proportionate.

Catgeory: 10th Class

NCERT Summary - Space Exploration

Space Exploration SPACE SCIENCE IN WORLD

The term "outer space" or "space" now usually refers to the vast limitless expanse that exists beyond the Earth's atmosphere.
Space contains all the stars, planets, gases and dust particles, meteorites, comets, asteroids and radiations.
The first step into space was taken on 4 October 1957 by the erstwhile Soviet Union (USSR), which successfully launched the first satellite named "Sputnik I" into space.
Satellite, in general, refers to celestial body that revolves around a planet. The moon, for example, is a natural satellite of the planet Earth. These days, however, the term satellite is used for man made satellites which revolve around the Earth.
The closed path of a satellite around the Earth is called its orbit. It may be circular or elliptical in shape.
The characteristics define an orbit are apogee, perigee and inclination. Apogee is the farthest and perigee is the nearest point on the orbit of a satellite from the Earth. The inclination of an orbit is determined by the angle it makes with the equator.
The USA followed the erstwhile Soviet Union and launched their first spacecraft a few months later. It was named "Explorer". Since then, space technology has made rapid progress. Not only have the satellites or other space probes called "payloads" grown many times in size and weight but their functions also have become more and more complex and demanding.
Within a few weeks of launching Sputnik I, the erstwhile USSR launched Sputnik II, which had the distinction of carrying a dog, named Laika, for the first time into space. The weight of the satellite was 500 kg. The blood pressure, temperature and heartbeat of Laika were monitored from the Earth for eight days, after which she was allowed to die peacefully as there was no possibility of bringing her back.
Sputnik II was successful in sending important data, which provided vital information and paved the way for sending the first human into outer space.
The erstwhile Soviet Union sent the first human into space. Yuri Gagarin completed a single orbit around the Earth on 12 April 1961. The USA followed the event on 5 May 1961, when Alan Shepard became the first American to go into space.
The main purpose of developing space technology included communication, resource, survey, meteorological studies, scientific experiments and most importantly, collecting information for military purposes, that is, for spying.
The significant development in space science during the eighties was the establishment of permanent space stations and the development of space shuttles (used to carry astronauts into space), establishing a permanent observatory in space and the maiden flight of Voyager II, which passed very close to all planets of the solar system and sent their pictures to the earth.
In Nineties (April 1992), another remarkable achievement was to carry out repair of a satellite in space by a team of American astronauts. Later, the repaired satellite was placed back in its original more...

Catgeory: 10th Class

Logic

Logic Logic The term “logic” came from the Greek word logos, which is sometimes translated as “sentence” “discourse”, “reason”, “rule”, and “ratio” Briefly speaking, we might define logic as the study of the principles of correct reasoning or the study of the principles of reasoning, especially of the structure of propositions as distinguished from their content and of method and validity in deductive reasoning. Proposition: In logic, any categorical statement is termed as the proposition. The standard form of proposition is consists of four parts

Quantifier
Subject
Copula
Predicate

Example: 1 All \[\to \] books \[\to \] are \[\to \] pens \[\downarrow \] \[\downarrow \] \[\downarrow \] \[\downarrow \] Quantifier \[\to \] subject \[\to \] copula \[\to \] predicate Example: 2 Some \[\to \] dog \[\to \] are \[\to \] cats \[\downarrow \] \[\downarrow \] \[\downarrow \] \[\downarrow \] Quantifier \[\to \] subject \[\to \] copula \[\to \] predicate Quantifier: The words which specify the quantity like ‘all’, ‘no’ and some.

Universal quantifier: The words ‘All and No’ are called universal quantifiers because they refer to every object in a certain set.

Particular quantifier: The word ‘Some’ is known as particular quantifier because it refers to at least one existing object in a certain set.

Subject (denoted by ‘S’): The subject is that about which something is said. Predicate (denoted by ‘P’): It is the part of the proposition denoting that which is affirmed or denied about the subject. Copula: It is the part of the proposition which denotes the relation between the subject and the predicate. Note: We should keep in mind that the quantifiers (‘all’, ‘no’, ‘some’) are implied in all categorical propositions even though they are not explicitly stated. If these quantifiers are not explicitly used in the formulation of the propositions it is aid to be in non-standard form. Quality: The kind of affirmation made by the proposition

Affirmative: asserts a quality to a class

Negative: denies a quality to a class

When we put the quality and quantity of categorical proposition together we see that there are four and only four possible arrangements:

Universal Affirmative
Particular Affirmative
Universal Negative
Particular Negative

Distribution: The quantity associated with either the subject or predicate term of a categorical proposition. Four-Fold Classification of Propositions A proposition, which begins with a universal quantifier, is said to have universal quantity. And a proposition, which begins with a particular quantifier, is said to have particular quantity. Besides, a proposition which asserts a quality to a class is called affirmative quality and a proposition which denies a quality to a class is called negative quality. Also, a term is distributed more...

Catgeory: 10th Class

Statements & Argument

Statement & Argument Statement - Argument In this part of logical reasoning a statement concerned with a social, political or economical issue is given along with two arguments - in favour of or against the statement. A strong argument is one which says the practical and real aspect of the situation as described in the statement, while the weak argument is ambiguous, superfluous and very simple. The candidate is required to analyze first the statement, then argument in context of the statement and finally decide which of the arguments is strong and is helping and to formulate the most appropriate opinion of the subject given in statement. Remember you are required to form an opinion only in the light of the given arguments and not on the basis of your own presumptions. Example: 1 1.

Statement:

Should luxury hotels be banned in big cities in India?

Arguments:

I. No affluent foreign tourists will have no place to stay.

II. Yes these are places from where international criminal operate.

(a) Only argument I is strong (b) Only argument II is strong (c) Either I or II is strong (d) Neither I nor II is strong (e) Both I and II are strong Ans. (a) Explanation: Argument I is strong because if the luxury hotels are banned in big cities in India, the affluent foreign tourists have no place to stay. Argument II is no strong because the check on international more...

Catgeory: 10th Class

Statements & Assumption

Statement & Assumption Statement-Assumption An assumption is something taken for granted i.e., a fact that can be supposed on considering the contents of the given statement. Type: 1 In this part of reasoning, a statement is given followed by two assumptions. The candidate is required to assess the given statement and then decide which of the given assumptions is implicit in the statement. Example: 1.

Statement:

Unemployment allowance should be given to all unemployed Indian youth above 18 years of age.

Assumptions:

I. There are unemployed youth in India who needs monetary support.

II. The government has sufficient funds to provide allowance to all unemployed youth.

(a) Only assumption I is implicit (b) Only assumption II is implicit (c) Either I or II is implicit (d) Neither I nor II is implicit (e) Both I and II are implicit Ans. (a) Explanation: Assumption I directly follows from the statement and so is implicit. Also, the statement is a suggestion and does not tell about a government policy or its position of funds. So, II is not implicit. 2.

Statement:

"If you trouble me, I will slap you, - A mother warns her child,

Assumptions:

more...

Catgeory: 10th Class

Statement - Courses of Action

Statement-Courses of Action Introduction Evaluating courses of action is a major area of logical reasoning. This type of questions is intended to scrutinize the decision-making skills of the candidate. Type-1 Problem Solution Relation In this type of pattern, the suggested course of action can be followed if.

It solves/ reduces or minimize the problem

The solution or course of action is practically possible.

A suggested course of actions can be said to solve/ reduce, minimize/ the problem. When; (a) It is an established fact: i.e., It is acknowledged universally as a fact. It is an established fact that accidents can be minimized if the motorists follow traffic rules. Example: 1 Statement: Accidents are increasing in the state of Kerala. Valid Course of Action: An awareness campaign conducted to make people aware of the importance of traffic rules. (b) Experiences says so: If previous experience predict that the particular course of action will minimize the problems, then it can be followed. (c) Logically it is right: If the problem given is a new one and hardly any experience can be attached to it, check whether the course of action is logically right. Example: 2 Statement: Reports say that the government jobs in rural areas are lying vacant. Course of Action: People working in rural areas should be given more incentives. This course of action is logically right. If incentives are given, people are motivated and hence they will go to rural areas. Now, the practicality test. A suggested course of action may indeed solve a problem but in practical life it may not be advisable or possible. If it is so, then the course of action is rejected. Example: 3 Statement: Accidents are increasing in our state. Course of action: The production of vehicles should be banned Though the above course of action minimizes the problem, it is practically impossible. Type-II Fact - Improvement Relation This pattern is solved just by applying the same rules of Type I. First we have to identify whether the fact or situation will improve due to the course of action mentioned. Second thing to do is to check whether the, course of action is practically possible. Important Tips We should never allow our personal perceptions to come into play while evaluating the suggested courses of action. We should always give importance to the way public departments and systems functions and we should accept them even if don’t trust them. Our decision and views should be impartial and impersonal. In most of the cases, a situation has more than one courses of action. But they are never exclusive of each other. So our answer “both follow” and not either of them follow”. Example:

Statement: Rapid growth of urban population has led more...

Catgeory: 10th Class

Situation Reaction Test

Situation Reaction Test Situation Reaction Test This test is mainly to judge a candidate's ability to use his presence of mind to tackle a given situation he may come across anytime in life. It judges the reasoning power of the candidate and his ability to act correctly and promptly to a situation that may arise in emergency. In this type of questions, certain situation is described and the candidate is required to choose the most suitable reaction to the given situation from amongst the alternatives provided. Example:

While playing football, suddenly when you kick the football, it strikes your friend’s nose resulting bleeding. You would:

(a) run away from the field (b) completely ignore it (c) blame somebody else for the accident (d) take the boy to the first aid room (e) None of these Ans. (d) Explanation: Clearly, in the above situation, the urgent need is to provide first aid to the boy so that bleeding may stop.

While passing by a pond. Raj hears the cry of a drowning child if he knows how to swim, he should:

(a) inform child's parents about the accident (b) dive into the pond to save him (c) immediately inform the police about the incident (d) look for professional divers (e) None of these Ans. (b) Explanation: Raj knows swimming so immediately he should dive into the pond and save the child.

Your bathroom tap is leaking and is a constant source of irritating noise. You would:

(a) sleep with pillows upon your ears. (b) put a bucket underneath (c) try to put up a cork upon the mouth of the tap. (d) call a plumber to repair the tap. (e) None of these Ans. (d) Explanation: In the above situation, you should call a plumber to repair the tap.

While sitting in a park, you observe that a man comes to the place on a motorbike, leaves it there and goes away with someone else in a car. You would:

(a) chase the person. (b) inform the police (c) call back the person. (d) remain engaged in your enjoyment. (e) None of these Ans. (b) Explanation: In the above situation, you should inform the police about the incident. Snap Test

Raman is playing football in a park. When he kicks the ball, it strikes and breaks the window pane of a nearby house. He should:

(a) stealthily run away from the park (b) demand his ball back from the house owner (c) stealthily get back his ball (d) apologies to the house owner and contribute more...

Catgeory: 10th Class