Topics
Chemical Substances - Nature and Behaviour
Carbon Compounds
- Carbon: a Versatile Element
- Bonding in Carbon - Covalent Bond
- Carbon: a Versatile Element
- Saturated and Unsaturated Carbon Compounds
- Chains, Branches and Rings of Carbon Compound
- Homologous Series of Carbon Compound
- Nomenclature of Carbon Compounds
- Chemical Properties of Carbon Compound
- Chemical Properties of Carbon Compound
- Chemical Properties of Carbon Compound
- Ethanol
- Ethanoic Acid
- Soap
- Chemical Properties of Carbon Compound
Metals and Non Metals
- Types of Element: Metals
- Types of Elements: Non-metal
- Chemical Properties of Metals: When Metals Are Burnt in Air
- Chemical Properties of Metals: When Metals React with Water
- Chemical Properties of Metals: When Metals React with Acids
- Chemical Properties of Metals: Metals React with Solutions of Other Metal Salts
- Chemical Properties of Metals: Reactivity Series
- Reaction of Metals with Non-metals
- Formation and Properties of Ionic Compounds
- Types of Element: Metals
- Extraction of Metals from Ore
- Enrichment of Ores
- Extracting Metals Low in the Activity Series
- Extracting Metals in the Middle of the Activity Series
- Extracting Metals Towards the Top of the Activity Series
- Refining of Metals
- Corrosion of Metals and Its Prevention
- Covalent (Molecular) Bond
Periodic Classification of Elements
Acids, Bases and Salts
- Acids
- Bases (Alkalis)
- Indicators
- Chemical Properties of Acids and Bases
- Reaction of Acids and Bases with Metals
- Reaction of Acids with Metal Carbonates and Hydrogencarbonates
- Reaction of Metallic Oxides with Acids
- Reaction of a Non-metallic Oxide with Base
- Acids and Bases React with Each Other
- Acid Or a Base in a Water Solution
- Strength of Acidic Or Basic Solutions
- Salts
- Salts
- Chemicals from Common Salt (Uses of Salt)
- Preparation and Uses of Sodium Hydroxide
- Preparation and Uses of Bleaching Powder
- Preparation and Uses of Baking Soda
- Preparation and Uses of Washing Soda
- Preparation and Uses of Plaster of Paris
Chemical Reactions
- Classification of Change: Physical Changes
- Classification of Change: Chemical Changes
- Classification of Change: Chemical Changes
- Chemical Equation
- Chemical Equation
- Direct Combination (or Synthesis)
- Decomposition Reactions
- Single Displacement Reactions
- Double Displacement Reaction
- Oxidation and Reduction
- Corrosion of Metals and Its Prevention
- Concept of Rancidity
- Endothermic and Exothermic Reactions
World of Living
Heredity and Evolution
- Evolution and Classification - Introduction
- Accumulation of Variation During Reproduction
- Heredity - Inherited Traits
- Rules for the Inheritance of Traits - Mendel’S Contributions
- Sex Determination in Humans
- Concepts of Evolution
- Evolution - Acquired and Inherited Traits
- Speciation
- Heredity and Evolution
- Evolution and Classification - Tracing Evolutionary Relationships
- Evolution and Classification - Fossils
- Evolution by Stages
- Human Evolution
Reproduction
- Reproduction in Plant
- Reproductive Health - Need and Methods of Family Planning
- Modes of Reproduction Used by Single Organisms - Fission
- Modes of Reproduction Used by Multicellular Organisms - Fragmentation
- Modes of Reproduction Used by Multicellular Organisms - Regeneration
- Modes of Reproduction Used by Single Organisms - Budding
- Modes of Reproduction Used by Multicellular Organisms - Vegetative Propagation
- Modes of Reproduction Used by Multicellular Organisms - Spore Formation
- Sexual Reproduction in Animals
- Sexual Reproduction in Flowering Plants
- Human Reproductive System
- Reproduction in Plant
- Sexually Transmitted Diseases
Control and Co-ordination in Animals and Plants
- Control and Co-ordination Introduction
- Tropic Movements in Plants
- Coordination in Plants - Movement Due to Growth
- Coordination in Plants - Immediate Response to Stimulus
- Hormones in Animals
- Control and Co-ordination in Animals
- Importance of Variation
- Animals – Nervous System
- Human Brain - Voluntary Action
- Human Brain - Involuntary Action
- Human Brain - Reflex Action
- Control and Co-ordination Questions
Life Processes
Natural Phenomena
- Refraction of Light
- Spherical Mirrors
- Concave Mirror
- Convex Mirror
- Concave Mirror
- Convex Mirror
- Sign Convention for Reflection by Spherical Mirrors
- Linear Magnification (M) Due to Spherical Mirrors
- Velocity of Light
- Refraction of Light
- Refraction Through a Rectangular Glass Slab
- Refractive Index
- Refraction by Spherical Lenses
- Convex Lens
- Concave Lens
- Convex Lens
- Concave Lens
- Sign Convention for Spherical Lenses
- Magnification of a Lens
- Power of a Lens
- Human Eye: Structure of the Eye
- Eye Defect and Its Correction: Myopia Or Near-sightedness
- Applications of Spherical Mirrors and Lenses
- Dispersion by a Prism
- Atmospheric Refraction
- Some Natural Phenomena Due to Sunlight
Effects of Current
Magnetic Effects of Current
- Magnetic Effect of Electric Current
- Magnetic Field Lines
- Magnetic Force
- The Bar Magnet
- Magnetic Field Due to a Current carrying Straight Conductor
- Right-Hand Thumb Rule
- Magnetic Field Due to a Current Through a Circular Loop
- Magnetic Field Due to a Current in a Solenoid
- Force on a Current Carrying Conductor in a Magnetic Field
- Fleming’s Left Hand Rule
- Electric Motor
- Electromagnetic Induction
- Alternating Current (A.C.) Generator
- Domestic Electric Circuits
- Types of current: Alternating Current (A.C.) and Direct Current (D.C.)
- Introduction of Magnetism
Effects of Current
Natural Resources
Management of Natural Resources
- Conservation and Judicious Use of Natural Resources
- Need to Manage Our Resources
- Forests and Wild Life - Stakeholders
- Forests and Wild Life - Sustainable Management
- Coal and Petroleum
- Water for All - Dams
- Water for All - Water Harvesting
- Overview of Natural Resource Management
- Sustainability of Natural Resources
- Fresh Water Management
Our Environment
Sources of Energy
- Sources of Energy Introduction
- Good Source of Energy
- Different Forms of Energy
- Conventional Sources of Energy
- Heat Energy (Thermal Energy)
- Hydroelectric Energy
- Improvements in the Technology for Using Conventional Sources of Energy
- Solar Energy
- Alternative or Non-conventional Sources of Energy - Energy from the Sea
- Alternative Or Non-conventional Sources of Energy - Geothermal Energy
- Nuclear Energy
- Environmental Consequences
- Energy Source - How Long Will Last Us
- Renewable and Non-renewable Energy Resources
notes
ELECTRIC MOTOR:-
-An electric motor is a rotating device that converts electrical energy to mechanical energy. Electric motor is used as an important component in electric fans, refrigerators, mixers, washing machines, computers, MP3 players etc.
-An electric motor consists of a rectangular coil ABCD of insulated copper wire. The coil is placed between the two poles of a magnetic field such that the arm AB and CD are perpendicular to the direction of the magnetic field
-The ends of the coil are connected to the two halves P and Q of a split ring. The inner sides of these halves are insulated and attached to an axle. The external conducting edges of P and Q touch two conducting stationary brushes X and Y, respectively
-Current in the coil ABCD enters from the source battery through conducting brush X and flows back to the battery through brush Y. Notice that the current in arm AB of the coil flows from A to B. In arm CD it flows from C to D, that is, opposite to the direction of current through arm AB.
-On applying Fleming’s left hand rule for the direction of force on a current-carrying conductor in a magnetic field
-We find that the force acting on arm AB pushes it downwards while the force acting on arm CD pushes it upwards. Thus the coil and the axle O, mounted free to turn about an axis, rotate anti-clockwise. At half rotation, Q makes contact with the brush X and P with brush Y. Therefore the current in the coil gets reversed and flows along the path DCBA
-A device that reverses the direction of flow of current through a circuit is called a commutator. In electric motors, the split ring acts as a commutator. The reversal of current also reverses the direction of force acting on the two arms AB and CD.
-Thus the arm AB of the coil that was earlier pushed down is now pushed up and the arm CD previously pushed up is now pushed down. Therefore the coil and the axle rotate half a turn more in the same direction. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil and to the axle.
-The commercial motors use
(i) an electromagnet in place of permanent magnet
(ii) large number of turns of the conducting wire in the current carrying coil
(iii) a soft iron core on which the coil is wound. The soft iron core, on which the coil is wound, plus the coils, is called an armature. This enhances the power of the motor.
