Topics
Chemical Substances - Nature and Behaviour
Carbon Compounds
- Concept of Carbon
- Bonding in Carbon - Covalent Bond
- Versatile Nature of Carbon
- 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 Compounds - Combustion
- Chemical Properties of Carbon Compounds - Addition Reaction
- Chemical Properties of Carbon Compounds - Substitution Reaction
- Properties of Ethanol
- Properties of Ethanoic Acid
- Soaps and Detergents
Metals and Non Metals
- Metal and Its Physical Properties
- Non Metals and Its Physical Properties
- 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
- Occurrence of 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
- Concept of Corrosion of Metals and Its Prevention
Periodic Classification of Elements
Acids, Bases and Salts
- Concept of Acid and Its Properties
- Concept of Base
- Acid and Base Indicator
- 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 Acids and Bases
- Concept of Salts
- Ph of Salts
- Chemicals from Common 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
- Concept of Physical Changes
- Concept of Chemical Changes
- Concept of Chemical Reactions
- Chemical Equation
- Balancing of a Chemical Equation
- Combination Reaction
- Decomposition Reactions
- Displacement Reaction
- Double Displacement Reaction
- Oxidation and Reduction
- Concept of 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
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
- Concept of Human Eye
- Defects of Vision and Their Correction
- 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 a 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 Acting on Current Carrying Conductor in a Magnetic Field
- Fleming’s Left Hand Rule
- Electric Motor
- Electromagnetic Induction
- Electric Generator - Ac
- Domestic Electric Circuits
- Alternating Current (AC) and Direct Current (DC)
- Introduction of Magnetism
Effects of Current
- Effects of Current Introduction
- Electric Current
- Electric Potential
- Electric Potential Difference
- Electric Circuit
- Ohm’s Law
- Factors on Which the Resistance of a Conductor Depends
- Resistance of a System of Resistors - Resistors in Series
- Resistance of a System of Resistors - Resistors in Parallel
- Heating Effect of Electric Current
- Electric Power
- Effects of Current Numericals
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
- Concept of Rainwater Harvesting (Importance)
Our Environment
Sources of Energy
- Sources of Energy Introduction
- Good Source of Energy
- Different Forms of Energy
- Conventional Sources of Energy
- Conventional Sources of Energy - Thermal Power Plant
- Conventional Sources of Energy - Hydro Power Plants
- Improvements in the Technology for Using Conventional Sources of Energy
- Alternative or Non-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
- Alternative or Non-conventional Sources of Energy - Nuclear Energy
- Environmental Consequences
- Energy Source - How Long Will Last Us
- Renewable Versus Non-renewable Sources
description
- Electric Fuses
- Principle of Fuse
description
- Joule's Law
- Practical Applications of Heating Effect of Electric Current
- Heating effect of electric current and its applications in daily life
notes
HEATING EFFECT OF ELECTRIC CURRENT:-
-A part of the source energy in maintaining the current may be consumed into useful work (like in rotating the blades of an electric fan). Rest of the source energy may be expended in heat to raise the temperature of gadget. We often observe this in our everyday life. For example, an electric fan becomes warm if used continuously for longer time etc.
-On the other hand, if the electric circuit is purely resistive, that is, a configuration of resistors only connected to a battery; the source energy continually gets dissipated entirely in the form of heat. This is known as the heating effect of electric current. This effect is utilised in devices such as electric heater, electric iron etc.
Cause of heating effect of electric current: Electric current generates heat to overcome the resistance offered by the conductor through which it passes. Higher the resistance, the electric current will generate higher amount of heat. Thus, generation of heat by electric current while passing through a conductor is an inevitable consequence. This heating effect is used in many appliances, such as electric iron, electric heater, electric geyser, etc.
JOULE’S LAW
-Consider a current I flowing through a resistor of resistance R. Let the potential difference across it be V Let t be the time during which a charge Q flows across. The work done in moving the charge Q through a potential difference V is VQ. Therefore, the source must supply energy equal to VQ in time t. Hence the power input to the circuit by the source is
P=`("VQ")/"T"="VI"`
-Or the energy supplied to the circuit by the source in time t is P × t, that is, Vit. This energy gets dissipated in the resistor as heat. Thus for a steady current I, the amount of heat H produced in time t is H = Vit ............(1)
We know that V=IR, substituting the value of V in eq 1
H=IR`xx`IT
H=I2RT
This is known as joules law of heating which states that heat produced in a resistor is directly proportional to the square of current given to the resistor, directly proportional to the resistance for a given current and directly proportional to the time for which the current is flowing through the resistor.
PRACTICAL APPLICATIONS OF HEATING EFFECT OF ELECTRIC CURRENT:-
-The electric laundry iron, electric toaster, electric oven, electric kettle and electric heater are some of the familiar devices based on Joule’s heating.
-The electric heating is also used to produce light, as in an electric bulb. Here, the filament must retain as much of the heat generated as is possible, so that it gets very hot and emits light. It must not melt at such high temperature. A strong metal with high melting point such as tungsten (melting point 3380°C) is used for making bulb filaments. The filament should be thermally isolated as much as possible, using insulating support, etc. The bulbs are usually filled with chemically inactive nitrogen and argon gases to prolong the life of filament. Most of the power consumed by the filament appears as heat, but a small part of it is in the form of light radiated.
-Another common application of Joule’s heating is the fuse used in electric circuits. It protects circuits and appliances by stopping the flow of any unduly high electric current. The fuse is placed in series with the device. It consists of a piece of wire made of a metal or an alloy of appropriate melting point, for example aluminium, copper, iron, lead etc. If a current larger than the specified value flows through the circuit, the temperature of the fuse wire increases. This melts the fuse wire and breaks the circuit. The fuse wire is usually encased in a cartridge of porcelain or similar material with metal ends.
Fuse of 1A, 2A, 3A, 5A, 10A, etc. are used for domestic purpose.