Download Alternative Sources of Energy

FORCE
Force
Force is defined as the push or pull that changes or tends to change the state of rest or
uniform motion of a body along a straight line.
Gravitation
The force of attraction between any two bodies in the universe is called gravitation or force of
gravitation.
Newton’s Universal Law of Gravitation
Newton’s Universal Law of Gravitation states that ‘Everybody in the universe attracts each
other with a force of gravitation which is directly proportional to the product of their masses
and inversely proportional to the square of the distance between their centers.’
Gravitational Constant
The force of attraction between two bodies of unit masses separated by a distance of 1m
between their centers is called gravitational constant. Its value is 6.67 x 10-11 Nm2/Kg2.
Gravity
The force with which the heavenly body attracts objects towards its centre is gravity.
#Note Gravity of the moon is 1/6 of the gravity of the earth
Gravity of the Jupiter is 2.5 times the gravity of the earth
Acceleration due to gravity
Acceleration due to gravity is the acceleration produced on a freely falling body due to the
gravity of the earth.
Its value is 9.83 m/s2 at poles and 9.78 m/s2 at equator but average value of acceleration due
to gravity is 9.8 m/s2
Gravitational Field
The space around a mass up to where its gravitational force can be experienced by other mass
is called gravitational field.
Gravitational Field Intensity
The force experienced by a unit mass placed at a point in gravitational field is the gravitational
field intensity at that point.
Mass
The amount of matter contained in a body is its mass. It is measured in kilogram.
Weight
Weight is the force with which it is attracted towards the center of the earth. It is measured in
Newton.
Freefall
When a body falls freely towards the centre of the earth under the influence of gravitational
pull of the heavenly body, then the motion is called freefall. It neglects air resistance.
Weightlessness
Weightlessness is the condition of the body when its weight seems to be zero i.e. the body
experiences zero reaction force.
PRESSURE
Pressure
Pressure is the force per unit area. It is measured in Pascal.
One Pascal Pressure
When one Newton force is applied to surface area of 1m2, the pressure at that point is one
Pascal pressure.
Pascal’s Law
When pressure is applied to liquid enclosed in a vessel, it is equally transmitted in all direction.
It is also known as principle of transmission of fluid pressure.
Up thrust or Buoyant force
When an object is partially or wholly immersed in a fluid, the force acting on the object by the
fluid is called up thrust or buoyant force.
Density
Mass per unit volume is called density.
Relative density
The ratio of density of any substance to the density of pure water at 4⁰C is relative density of
that substance.
Archimedes Principle
Archimedes Principle states that when a body is partially or wholly immersed in liquid, it
experiences an up thrust which is equal to the weight of the liquid displaced by it.
Law of floatation
Law of floatation states that weight of a floating body is equal to the weight of fluid displaced
by the body.
Hydrometer
Hydrometer is device which is used to measure the specific gravity and density of liquids.
SOURCES OF ENERGY
Fuel
The substance that reacts chemically with another substance to produce heat by nuclear
process is called fuel.
Primary sources of energy
Those sources of energy which can be used in the same form in which they occur in nature are
called primary sources. Example: wood, crude oil, etc.
Secondary sources of energy
Those sources of energy which are derived from primary sources of energy are called
secondary sources. Example: petroleum, charcoal, etc.
Non Renewable Energy Sources
Non renewable energy sources are those sources which are accumulated in nature for long
time and cannot be quickly replaced when exhausted at their origin place.
Fossil Fuels
Millions of years ago when plants and animals died they got buried under sand and clay, due
to high temperature and pressure inside the earth, they got decomposed in absence of
oxygen. They formed fossil fuel after decomposition.
Coal
The dead plants and animals which got buried in deep mines, millions of years ago, were
decomposed in absence of oxygen and presence of high temperature and pressure. And
formed coal.
Nuclear Energy
When a heavy nuclei splits or light nuclei combines there is tremendous amount of energy
released in the form of heat and light called nuclear energy.
Nuclear Fission
When a heavy nuclei is bombarded with slow neutron it releases large amount of energy. This
process is called nuclear fission.
Nuclear Fusion
When light nuclei combine to form heavy nuclei large amount of energy is released. This
process is called nuclear fusion.
Thermo nuclear fission
When a heavy nuclei is bombarded with slow neutron in presence of heat large amount of
energy is released. This process is called thermo nuclear fission.
Thermo nuclear fission
When light nuclei combine to form heavy nuclei in presence of heat large amount of energy is
released. This process is called thermo nuclear fusion.
Renewable Sources of Energy.
The sources of energy that can be replaced immediately if they are exhausted at their origin
place are called renewable sources of energy.
Bio fuel
The energy obtained from the bio mass is called bio fuel.
Geo Thermal Energy
In the volcanic or earthquake regions the surface temperature rises by 80⁰C per kilometer, if a
hole is drilled and water is allowed to pass through the hole, it instantly gets converted into
steam which comes out forcibly and rotates the turbines of generator to produce electricity.
This energy is called Geo thermal energy.
Solar Constant
The solar energy received by the earth per square meter which is estimated to be 1.4 kw is
called solar constant.
Energy Crisis
The future scarcity of energy sources on the earth due to over population, urbanization and
industrialization is called energy crisis.
Alternative Sources of Energy
The sources of energy which can be used to preserve the non renewable sources of energy for
the future is called alternative source of energy.
HEAT
Heat
Heat is a form of energy that flows from a hot body to cold body when they are kept in
thermal contact.
Internal Energy
Sum of kinetic energy of all molecules is called internal energy.
Heat in terms of molecular theory
The total kinetic energy possessed by all the molecules of a body is called heat.
Temperature
The degree of hotness or coldness of a body is called temperature.
Temperature in terms of molecular theory
The average kinetic energy of the molecules is called temperature.
One Calorie heat
The amount of heat required to raise the temperature of 1 gram of pure water by 1⁰C or 1⁰K is
one calorie heat.
Anomalous Expansion of Water
The unusual behavior of water that expands on cooling from 4⁰C to 0⁰C is called anomalous
expansion of water.
Heat Equation
Heat Equation states that the product of mass, specific heat capacity and change in
temperature is equal to the heat gained or heat lost.
Principle of Caloriemetry
Principle of Caloriemetry states that when two bodies are kept on thermal contact the heat
flows from hot body to cold body, which continues until they attain the same temperature.
Thermal Capacity
The amount of heat required to raise the temperature of the body by 1⁰C is the thermal
capacity of a body.
Specific heat capacity
The amount of heat required to raise the temperature of unit mass of body by 1⁰C is called
specific heat capacity of that body.
Absolute Zero Temperature
Absolute zero temperature is the temperature at which the thermodynamic system has the
lowest energy. It corresponds to -273.15⁰C on the Celsius temperature scale and -459.67⁰F on
the Fahrenheit temperature scale.
LIGHT
Lens
Lens is an optical device made by transparent refracting medium bounded by spherical
surface.
Convex Lens
The lens which is thicker at centre and thinner at edges is convex lens. It is called converging
lens because it converges the parallel beam to a point after refraction.
Concave Lens
The lens which is thinner at centre and thicker at edge is concave lens. It is called diverging
lens because it diverges parallel bean from a point after the refraction.
Centre of curvature
The centre of the sphere forming lens is called centre of curvature.
Principal Axis
It is the straight line which passes through two centre of curvature.
Optical centre
The geometrical centre of lens is called optical centre.
Principal Focus
When a parallel beam of light is incident in a lens parallel to principal axis, they seem to
appear or meet at a point on the principal axis after refraction through the lens is called
principal focus.
Focal Length
It is the distance between the principal focus and optical centre of lens.
Focusing
The process of making a sharp image on a screen with a convex lens by changing the distance
between the lens and its screen is called focusing.
Real Image
The image formed by real intersection of refracted rays and can be obtained on a screen is real
image.
Virtual Image
The image that is formed by apparent intersection of refracted rays and cannot be obtained on
the screen is virtual image.
Magnification
Magnification of a lens is defined as the ratio of height of the image to the height of the
object.
Power of lens
The power of lens is its capacity to converge or diverge light rays falling on it.
or
The reciprocal of its focal length expressed in meter is power of lens.
Simple Camera
It is a real image forming optical instrument that is used to take photograph of objects and
people.
Eye
Eyes are natural real image forming optical instrument which are related to sense of vision.
Yellow Spot
It is the point of retina which is rich in rod and cone cells and the image of object is formed in
it.
Blind Spot
It is the point of retina which is poor in rod and cone cells and image is not formed in it.
Optic Nerve
It is the nerve that carries the impulses to the brain.
Near Point
The nearest point which an object can be seen clearly by eyes is near point.
Least distance of distinct vision
The distance of the near point from the eye is called the least distance of distinct vision. It is
25cm for a normal eye.
Far point
The farthest point up to which objects can be seen clearly is called far point.
Power of accommodation
The ability of the eye to change the focal length of the eye so as to obtain the image at the
retina is called power of accommodation.
Persistence of vision
The effect of vision in which the impression of the image lasts on the retina even after the
removable of the object is called persistence of vision.
Defect of vision
An eye which does not form the image of object lying between near point and far point on
retina is said to suffer from defect of vision.
Long Sightedness (Hypermetropia)
It is the defect of vision in which person cannot see distant object distinctly but can see nearby
object clearly.
Short Sightedness (Myopia)
It is the defect of vision in which person can see near object clearly but cannot see the distant
object distinctly.
Microscope
It is a virtual image forming optical instrument which is used to see the magnified image of
small object placed very close to it.
Telescope
It is a virtual image forming optical instrument which is used to see distant object clearly.
ELECTRICITY AND MAGNETISM
Electric Circuit
The path of electricity through which it flows to conduct different electrical appliances is called
electric circuit.
Closed Circuit
The circuit in which switch is closed and electricity flows in it is called closed circuit.
Open Circuit
The circuit in which switch is open and electricity does not flow in it is called open circuit.
Series Combination of cells
If positive terminal of one cell is connected to the negative terminal of the second and so on
then such combination of cells is called series combination.
Parallel Combination of cells
If the positive terminals of all cells are connected together at a common point and negative
terminal at another common point. Then such combination of cells is called parallel
combination.
Series Combination of Resistor
When number of resistors in a circuit is connected from end to end in a circuit is called series
combination of resistor.
Parallel Combination of Resistor
When a number of resistors in a circuit are connected between two common points then such
combination is parallel combination.
Equivalent Resistance
The single resistance which can replace the combination of resistance without changing the
current in the circuit is called equivalent resistance.
Electric Power
Electric power is the rate at which electrical energy is converted to other form of energy.
Current Rating
The maximum current that can be passed through the wire safely is called its current rating.
Over loading
When more electric current flows through a wire than its current rating than the wire may
burn or damage is called over loading.
Short Circuiting
When positive and negative terminal of the electric source comes in contact the total
resistance becomes low and very large current flows in the circuit. This is known as short
circuiting.
Fuse
Fuse is an alloy of tin and lead, having low melting point, and is connected in the series with
the circuit to protect the circuit from excessive heating.
Direct Current
The current whose polarity does not change with time is called direct current. Eg: Battery and
Dynamo
Alternating Current
The current whose magnitude changes continuously and reverses its direction periodically is
called alternating current.
Heating Effect
When electric current is converted into heat energy then such effect is called heating effect.
Heating Element
The coil having high resistance and high melting point used in the heater to convert the
electrical energy to heat energy is called the heating element.
Lighting Effect
When electric current is passed through some electrical appliances they change electrical
energy into light energy such effect is called lighting effect.
Filament
The tungsten coil used in filament lamp having high melting point and high resistance which
convert electrical energy into light energy is called filament.
Magnetic Effect
When an electric current is passed through a conductor it behaves like a magnet, this effect is
called magnetic effect of electric current.
Right hand grip rule
It is the rule which states that if the solenoid is gripped by right hand in such a way that the
fingers are in the direction of the current flowing in the wire, the thumb points the north pole
of it.
Solenoid
The spiral arrangement of an insulated wire is called solenoid.
Electromagnet
A solenoid behaves like a magnet during the flow of electric current through it. This is known
as electromagnet.
Chemical Effect
When current is passed through a liquid, it undergoes some chemical changes. The effect is
called chemical effect.
Electrolysis
Electrolysis is the process of decomposition of an electrolytic solution into its constituent
passing an electric current through it.
Electroplating
Electroplating is process of depositing a thin layer of a metal over a conducting surface by the
process of electrolysis.
Magnetic Flux
Magnetic flux through a surface is the number of magnetic lines of force passing through the
surface held perpendicular to the lines of force.
Electromagnetic Induction
Whenever the magnetic flux linked with a closed circuit changes, an emf is induced in the
circuit. This phenomenon is called the electromagnetic induction.
Induced current
The current obtained by a circuit due to electromagnetic induction is called induced current.
Fleming’s Right Hand Rule
Fleming‘s Right Hand Rule is used to determine the direction of the induced current in a
generator. It states that when first three fingers of right hand are held perpendicular to each
other, the index finger shows direction of magnetic flux, thumb shows the direction of motion
of coil, and middle finger shows the direction of induced current.
Motor Effect
When a current carrying a conductor is kept in a magnetic field the conductor moves if it is
allowed to do so, this is called motor effect.
Electric Motor
The machine used to convert electrical energy into mechanical energy is called electric motor.
Transformer
A transformer is a device that converts low AC voltage into high AC voltage and vice versa
Step Up transformer
The transformer that converts low AC voltage into high AC voltage is step up transformer.
Step down Transformer
The transformer that converts high AC voltage into low AC voltage is step down transformer.
Principle of mutual induction
When alternating emf is provided to primary coil an alternating magnetic flux is created which
induces alternating emf in the secondary coil. This principle is called principle of mutual
induction.
Ohm’s Law
Ohm’s law states that the current through a conductor between two points is directly
proportional to the voltage across the two points.
SUMAN MAHARJAN
HEAD OF SCIENCE DEPARTMENT