drives and control every apects of
human life.It is crucial for continued human
development and growth.Growth and
develpoment are directly related to the
availability of cheap and affordable energy.
The standard of living can be correlated to
the use of energy. Life is unthinkable without
Mechanical energy constitutes of both kinetic
energy and potential energy.
energy possessed due to motion of an
object is known as kinetic energy.Kinetic
energy is of various forms such as vibrational
. Rotational , translational and so on.
Kinetic energy of an object having mass m
moving with the velocity v along the
horizontal direction is given by
energy is the stored energy and is
capable of doing work.Consider a ball of
mass m held at a height h above the
ground.The ball possesses potential energy
due to its height given by:
Now,if the ball is allowed to fall under the
field of gravity,it will start accelerating
towards the ground,the ball will have both
potential energy and kinetic energy and is
given by E=P.E+K.E
energy stored in the form of chemical
bonds of a compound is known as chemical
energy is stored as electromagnetic
forces of attraction between the atoms,ions
or molecules takes place which results in
releasing or absorbing of energy.
the total energy of the reactants is more
than that of the products,the additional
energy is released and the reaction is known
as an exothermic reaction.
If the energy of the reactants is less than
that of the products,the energy is absorbed
and the reaction is called an endothermic
Thus ,the energy arising during a chemical
reaction is known as the chemical energy
battery stroes electrical energy in the form
of the chemical energy.
During a chemical reaction,ions are formed
which accumulate at different electrodes of
the battery. Once this battery is connected
to an external circuit, a current is setup in
the circuit. Thus,the accumulated charges
are used to drive electrical circuits of various
Electricity is an integral part of modern society.
Consider any modern technology and you will see that it is
directly or indirectly dependent on electricity.
Electricity is one of the main forms of the energy produced
Since fossil fuels are steadily running out,electric power will be
one of the most important energy forms in the future.
All materials are made of atoms.The atoms further consist of a
nucleus(with protons and neutrons) at the centre and electrons
orbiting around the nucleus.
All metal atoms contain some fixed number of loosely bound
electrons. On applying a potential difference across these
metals, these electrons start moving within the surface of the
metal with an average velocity k/a drift velocity. This leads to
Generally,copper and aluminum are used for making electrical
wires since these metals have a lower resistance in comparison to
EM waves are defined as packets of energy
Each photon has a specific wavelength and
The energy associated with these is k/a
electromagnetic energy and is given by
Where h is Planck’s constant and has a value
Energy sources which can not be replenished in a
short period of time.
Some Non Renewable energy sources are:-
They are formed by the decay of dead animal and
plant which was buried under the earth hundreds of
thousands year ago. Example- coal and natural gas.
Apart from their limited stocks, the use of fossil fuel
also increase the concentration of CO2 in the
atmosphere which enhances the green house effect
and global warming. This leads to climatic changes.
The strong forces b/w the nucleons holds the nucleus together.
Any change occurring in the nuclear structure results in the
liberation of high amounts of energy k/a nuclear energy.
The process in which 2 nucei fuse together is called nuclear
fusion. This process yields large amount of energy. Eg- Nuclear
fusion b/w hydrogen nuclei in sun leads to formation of helium
Also vast amount of energy is released when an unstable heavy
nucleus splits into smaller nuclei. This process is k/a nuclear
fission. Eg – In a nuclear power plant, uranium nuclei break apart
into smaller nuclei while releasing energy. The nuclear energy is
not only due to potential energy during rearrangement of nuclei
but also due to conversion of matter making up the nuclei.
Energy liberated from nuclear fission and fusion
is 107 higher compared to energy obtained from
fossil fuel for the same amount of matter.
Moreover energy released is cleaner compared to
that of fossil fuels.
The notable problem is that it leads to
radioactive spent fuel waste. Radioactive waste
management is one of the intractable problem
faced worldwide. This waste should not enter
the biosphere as it can affect the ecosystem.
sources which can be generated using
naturally occurring sources are k/a
renewable sources of energy.
Some example of Renewable Sources of
The energy obtained from sun is k/a solar energy. It can
be used in solar water heaters, solar cookers, and solar
electric generators. Solar electricity generator converts
solar energy into electric energy with the help of
Its benefits are that the sunlight is widely and easily
available and it can cater to the electricity needs.
The problem is that it requires huge investments and
bad weather conditions pose interruption to supply of
potential energy possessed by wind is
converted to mechanical energy with the
help of windmills which finally generate
A large area is required with no or very less
population and where wind speed is high (7-9
Costly to setup.
potential energy possessed by water is
converted to mechanical energy by turbines
which finally generate electricity.
However, the dams and other structures are
required for these which are not cost
heat energy present within the earth
helps to generate electricity using
geothermal energy plants. Water is pumped
into the ground where it comes into contact
with hot rocks which leads to formation of
steam which is further used to generate
electricity. Problem- Sites available for
geothermal energy is limited.
energy is harnessed by making
structures which are capable of rotating the
turbine in order to produce electricity with
the help of change in water level.
is always conserved- it can neither be
created nor be destroyed…it can only be
transformed from one form to another. But the
problem is that during all transformatios some
energy is lost into the surroundings in the form of
heat, light and sound which cannot be recovered.
Moreover non renewable resources are limited.
Therefore the energy resources need to be
Some ways in which energy can be conserved
1) Turn off lights and fans when not in use.
2) Car pooling, using public transport will reduce
fuel consumption .
3) Use more of renewable energy as they are
available in plenty and do not pollute the
4) Employ energy or carbon taxes to motivate
energy users to reduce their consumption.The
State of California employs a tiered energy tax
whereby every consumer receives a baseline
energy allowance that carries a low tax. As usage
increases above that baseline, the tax increases
5) One of the primary ways to improve energy
conservation in buildings is to use an energy
audit. An energy audit is an inspection and
analysis of energy use and flows for energy
conservation in a building, process or system
to reduce the amount of energy input into
the system without negatively affecting the
output(s). This is normally accomplished by
6) Replace a regular incandescent light bulb with a
compact fluorescent light bulb
CFLs use 60% less energy than a regular bulb. This
simple switch will save about 300 pounds of carbon
dioxide a year.
7)Wrap your water heater in an insulation blanket
You’ll save 1,000 pounds of carbon dioxide a year
with this simple action. You can save another 550
pounds per year by setting the thermostat no higher
8) Move your fridge and freezer
Placing them next to the cooker or boiler
consumes much more energy than if they were
standing on their own. For example, if you put
them in a hot cellar room where the room
temperature is 30-35ºC, energy use is almost
double and causes an extra 160kg of CO2
emissions for fridges per year and 320kg for
9) Take a shower instead of a bath
A shower takes up to four times less energy than
a bath. To maximise the energy saving, avoid
power showers and use low-flow showerheads,
which are cheap and provide the same comfort.
10) Recycle your organic waste
Around 3% of the greenhouse gas emissions through
the methane is released by decomposing biodegradable waste. By recycling organic waste or
composting it if you have a garden, you can help
eliminate this problem! Just make sure that you
compost it properly, so it decomposes with sufficient
oxygen, otherwise your compost will cause methane
emissions and smell foul.
11) Reuse your shopping bag
When shopping, it saves energy and waste to use a
reusable bag instead of accepting a disposable one in
each shop. Waste not only discharges CO2 and
methane into the atmosphere, it can also pollute the
air, groundwater and soil.