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NCERT Chapter Summary: Some Basic Concepts of Chemistry

Chemistry, as we understand it today is not a very old discipline. People in ancient India, already had the knowledge of many scientific phenomenon much before the advent of modern science. They applied the knowledge in various walks of life.

NCERT Chapter Summary: Hydrocarbons

Hydrocarbons are the compounds of carbon and hydrogen only. Hydrocarbons are mainly obtained from coal and petroleum, which are the major sources of energy.

NCERT Chapter Summary: Organic Chemistry - Basic Principles and Techniques

Organic compounds are formed due to covalent bonding. The nature of the covalent bonding in organic compounds can be described in terms of orbitals hybridisation concept, according to which carbon can have sp³, sp² and sp hybridised orbitals.

NCERT Chapter Summary: Redox Reactions

Redox reactions form an important class of reactions in which oxidation and reduction occur simultaneously.

NCERT Chapter Summary: Equilibrium

When the number of molecules leaving the liquid to vapour equals the number of molecules returning to the liquid from vapour, equilibrium is said to be attained and is dynamic in nature.

NCERT Chapter Summary: Chemical Thermodynamics

Thermodynamics deals with energy changes in chemical or physical processes and enables us to study these changes quantitatively and to make useful predictions. For these purposes, we divide the universe into the system and the surroundings.

NCERT Chapter Summary: Classification of Elements and Periodicity in Properties

Mendeleev’s Periodic Table was based on atomic masses. Modern Periodic Table arranges the elements in the order of their atomic numbers in seven horizontal rows (periods) and eighteen vertical columns (groups or families).

NCERT Chapter Summary: Structure of Atom (Class 11)

Atoms are the building blocks of elements. They are the smallest parts of an element that chemically react. The first atomic theory, proposed by John Dalton in 1808, regarded atom as the ultimate indivisible particle of matter.

NCERT Chapter Summary: Electric Charges and Fields

Electric and magnetic forces determine the properties of atoms, molecules and bulk matter.

NCERT Chapter Summary: Semiconductor Electronics

Semiconductors are the basic materials used in the present solid state electronic devices like diode, transistor, ICs, etc.

NCERT Chapter Summary: Atoms

Atom, as a whole, is electrically neutral and therefore contains equal amount of positive and negative charges.

NCERT Chapter Summary: Dual Nature of Radiation and Matter

The minimum energy needed by an electron to come out from a metal surface is called the work function of the metal. Energy (greater than the work function (φ_ο) required for electron emission from the metal surface can be supplied by suitably heating or applying strong electric field or irradiating it by light of suitable frequency.

NCERT Chapter Summary: Wave Optics

Huygens’ principle tells us that each point on a wavefront is a source of secondary waves, which add up to give the wavefront at a later time.

NCERT Chapter Summary: Ray Optics and Optical Instruments

Reflection is governed by the equation ∠i = ∠r′ and refraction by the Snell’s law, sini/sinr = n, where the incident ray, reflected ray, refracted ray and normal lie in the same plane.

NCERT Chapter Summary: Electromagnetic Waves

Maxwell found an inconsistency in the Ampere’s law and suggested the existence of an additional current, called displacement current, to remove this inconsistency. This displacement current is due to time-varying electric field.

NCERT Chapter Summary: Alternating Current

An alternating voltage v = v_m sin ωt applied to a resistor R drives a current i = i_m sin ωt in the resistor, i_m = v_m/R. The current is in phase with the applied voltage.

NCERT Chapter Summary: Electromagnetic Induction

The magnetic flux through a surface of area A placed in a uniform magnetic field B is defined as, Φ_B = B.A = BA cos θ where θ is the angle between B and A.

NCERT Chapter Summary: Magnetism and Matter

The science of magnetism is old. It has been known since ancient times that magnetic materials tend to point in the north-south direction; like magnetic poles repel and unlike ones attract; and cutting a bar magnet in two leads to two smaller magnets. Magnetic poles cannot be isolated.

NCERT Chapter Summary: Moving Charges and Magnetism

The total force on a charge q moving with velocity v in the presence of magnetic and electric fields B and E, respectively is called the Lorentz force.

NCERT Chapter Summary: Motion in a Plane

Motion in a plane is the motion in two dimensions, for instance, projectile motion, circular motion and so on.

NCERT Chapter Summary: Units and Measurement

Some of the common systems of units that are used in physics are: CGS system, FPS system, MKS system, and SI system.

NCERT Chapter Summary: Waves

There are four types of waves - mechanical, transverse, longitudinal, progressive.

NCERT Chapter Summary: Oscillations

Oscillation is a measure of some repetitive variation, as a function of time. It can be measured with respect to a state of equilibrium. The most common and simplest example for oscillation is the motion of a simple pendulum.

NCERT Chapter Summary: Kinetic Theory

The kinetic theory of gases explains the behavior of molecules, which should further explain the behavior of an ideal gas. Ideal Gas equation consists of the pressure (P), volume (V), and temperature (T) of gases at low temperature and the equation is: PV = nRT.

NCERT Chapter Summary: Thermodynamics

Thermodynamics is concerned with the relationship between other forms of energy and heat. It explains how thermal energy is converted from other forms of energy. The energy coming from heat is termed thermal energy. When the tiny particles within an object move, they generate heat, more amount of heat is generated, when these particles move at a faster pace.

NCERT Chapter Summary: Thermal Properties of Matter

By definition, matter or material is anything that has mass and occupies space. Everything we see around us is matter. For example, a water bottle is made up of plastic or any metal, both of which are examples of matter.

NCERT Chapter Summary: Mechanical Properties of Fluids

Fluids are the substances which move or flow in a certain direction when an external force is applied to them. Fluids can be either gases or liquids. However, when you study fluids and their mechanical properties, you come across two topics namely hydrodynamics and hydrostatics.

NCERT Chapter Summary: Mechanical Properties of Solids

What happens to a rubber band when you stretch it and let go? It deforms but regains its original nature when you stop applying a force. But say, you take an aluminium rod and try to bend it using your arm strength. You somehow do manage to bend it a little and then stop applying force. Does the rod regain its original shape? Of course not.

NCERT Chapter Summary: Gravitation (Class 11)

Gravitation or gravity is a naturally occurring phenomenon or a force which exists among all material objects in the universe.

NCERT Chapter Summary: Systems of Particles and Rotational Motion

Imagine a rectangular block placed on the slanting edge of a right-angled triangle. If the block is assumed to slide down this edge without any side movement, every point in the rectangular block experiences the same displacement and more importantly, the distance between the points is also maintained.

NCERT Chapter Summary: Work, Energy and Power

Work is the measurement of energy transfer that takes place when an object is displaced by an external force applied in the direction of the displacement.

NCERT Chapter Summary: Development

Different persons can have different developmental goals. What may be development for one may not be development for the other. It may even be destructive for the other.

NCERT Chapter Summary: Globalisation and the Indian Economy

Globalisation is the process of rapid integration of countries. This is happening through greater foreign trade and foreign investment. MNCs are playing a major role in the globalisation process.

NCERT Chapter Summary: Money and Credit

In a barter system where goods are directly exchanged without the use of money, double coincidence of wants is an essential feature. In contrast, in an economy where money is in use, money by providing the crucial intermediate step eliminates the need for double coincidence of wants.

NCERT Chapter Summary: Sectors of Indian Economy

When we produce a good by exploiting natural resources, it is an activity of the primary sector. Since most of the natural products we get are from agriculture, dairy, fishing, forestry, this sector is also called agriculture and related sector.

NCERT Chapter Summary: Story of Village Palampur

Farming is the main production activity in the village. Over the years there have been many important changes in the way farming is practiced. These have allowed the farmers to produce more crops from the same amount of land.

NCERT Chapter Summary: People as Resource

Inputs like education and health helped in making people an asset for the economy. Investment in human capital (through education, training, medical care) yields a return just like investment in physical capital.

NCERT Chapter Summary: Food Security in India

Food security of a nation is ensured if all of its citizens have enough nutritious food available, all persons have the capacity to buy food of acceptable quality and there is no barrier on access to food.

NCERT Chapter Summary: Poverty as a Challenge

Poverty has many dimensions. Normally, this is measured through the concept of poverty line. A common method used to measure poverty is based on the income or consumption levels. Through this concept we analysed main global and national trends in poverty.

NCERT Chapter Summary: Power Sharing

In a democracy, all power does not rest with any one organ of the government. An intelligent sharing of power among legislature, executive and judiciary is very important to the design of a democracy.

NCERT Chapter Summary: Outcomes of Democracy

We face a dilemma: democracy is seen to be good in principle, but felt to be not so good in its practice. This dilemma invites us to think hard about the outcomes of democracy.

NCERT Chapter Summary: Political Parties

A political party is a group of people who come together to contest elections and hold power in the government. They agree on some policies and programmes for the society with a view to promote the collective good. Parties reflect fundamental political divisions in a society.

NCERT Chapter Summary: Gender, Religion and Caste

The existence of social diversity does not threaten democracy. Political expression of social differences is possible and sometimes quite desirable in a democratic system. Three kinds of social differences that can take the form of social divisions and inequalities are social differences based on gender, religion and caste.

NCERT Chapter Summary: Democratic Rights

Rights are reasonable claims of persons recognised by society and sanctioned by law. Rights are necessary for the very sustenance of a democracy.

NCERT Chapter Summary: Working of Institutions

President is the head of the state and is the highest formal authority in the country. Prime Minister is the head of the government and actually exercises all governmental powers. He takes most of the decisions in the Cabinet meetings.

NCERT Chapter Summary: Constitutional Design

The constitution of a country is a set of written rules that are accepted by all people living together in a country. Constitution is the supreme law that determines the relationship among people living in a territory (called citizens) and also the relationship between the people and government.

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