Physics Notes in the form of Question-answer

The branch of science concerned with the nature and properties of matter and energy
Ans: Physics
Scientists have known as fathers of Physics
Ans: Einstein, Newton, and Galileo
*Father of Nuclear Physics
Ans: Ernest Rutherford

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UNITS AND MEASUREMENTS

*The chosen standard used for measuring a physical quantity is called
Ans : Unit
*Units are classified into
Ans : Two
*Two types of Units are
Ans : Fundamental Units and Derived Units
*The Units of fundamental quantities which can’t be derived from any other quantities
Ans : Fundamental Units
*Fundamental units can be expressed in 3 kinds of measuring systems such as
Ans : CGS, MKS and FPS

The Units which are derived from fundamental units
Ans: Derived Units

FUNDAMENTAL UNITS
Measurement CGS MKS FPS
Length Centimeter Meter Foot
Mass Gram Kilogram Pound
Time Second Second Second

*Modified form of MKS System
Ans : SI (System International)
*Globally approved form of unit system
Ans : SI system
*Physical quantities are divided into
Ans : Scalar quantity & Vector quantity
*Physical quantity having only magnitude, but no direction
eg : Mass, Length, Time etc
Ans : Scalar quantity
*Physical quantity having both magnitude and direction
eg: Velocity, Momentum, Force etc
Ans : Vector quantity
*Einstein proposed the General Theory of Relativity in
Ans : 1915

MOTION
*The change in position of an object over time is called
Ans : Motion
*Actual length travelled by a body is called Distance
Shortest distance from the initial to the final position of a body is called
Ans : Displacement

MECHANICS
*The study of particles or bodies when they are at rest or in motion is dealt with
Ans: Mechanics
*Mechanics is divided into two
Ans: Statics & Dynamics
*The study of objects of rest is called
Ans: Statics
*The study of moving objects is called
Ans: Dynamics

KINETICS AND KINEMATICS
*Kinetics and Kinematics are the subdivisions of
Ans : Dynamics
*Kinetics deals with relationship between the motion of bodies and forces acting on them
*Kinematics is the study of the relationship between displacements, velocity, acceleration and time of a given motion, without considering the forces that cause the motion

Parameters Formula Unit Speed
*Speed Distance/Time m/s
*Velocity Displacement/Time m/s
*Acceleration Change in Velocity/Time m/s

TYPES OF MOTION EXAMPLE

• Translator motion – Moving vehicles
• Rectilinear motion – Motion of lift
• Curvilinear motion – Motion of rocket
• Circular motion – Spinning wheel
• Oscillatory motion – Movement of swing
• Periodic motion – Rotation of earth
• Simple harmonic motion – Pendulum
• Circular Motion – Orbits of planets

MOMENTUM

• The product of mass and velocity of a body
  Ans : Momentum
  P = mv [m=Mass, v=velocity]
• It’s a vector quantity
• Unit – kg m/s
• A Karate player in order to break a brick hits quickly because of
  Ans : Momentum

NEWTON’S LAWS OF MOTION
*Newton established the laws of motion in his book
Ans : ‘Principia Mathematica’

FIRST LAW OF MOTION
*Every body continues in its state of rest or uniform motion along a straight line unless compelled by an external unbalanced force
*This law is based on Galileo’s law of inertia
eg : Passenger in a bus

SECOND LAW OF MOTION
*Rate of change of momentum is directly proportional to the external unbalanced force
*It is used to express force
*Represented by the equation F = Ma (F = Force, M = Mass, a = Acceleration)

THIRD LAW OF MOTION
*For every action there is an equal and opposite reaction
eg : Propulsion of rocket, Swimming, Flying Birds etc.

INERTIA
*A property of a body which is unable to change its state by itself in the absense of external force called
Ans : Inertia
*The Law of inertia was discovered by
Ans : Galileo
*There are three types of inertia
Ans : Inertia of Rest, Inertia of Motion and Inertia of Direction
*Example of Inertia of motion
Ans : An athlete runs some distance before taking a long jump
*Example of Inertia of rest
Ans : As the train starts moving, a man sitting inside leans backward
*Example of Inertia of direction
Ans : Rotating wheel of an automobile throw out mud tangentially outward

ROTATION AND REVOLUTION
*If a rotating body spins on its axis, its motion is called
Ans : Spin motion or rotation motion
eg: The earth spins on its own axis in 24 hrs
*When an object travels around another object it is known as
Ans: Revolution
eg: The Earth revolving around the sun

PROJECTILE MOTION
*The motion of an object in a vertical plane under the influence of gravitational force is known as
Ans : Projectile motion
*Projectile path is known as
Ans : Trajectory
*A projectile reaches maximum range, when angle of projection is at
Ans : 45°
*The path of the projectile is always a
Ans : Parabola

FORCE
*An influence that changes the state of rest in a straight line of a body is called – Force
Ans : F = ma

*Unit – Newton or Kg m/s2
*CGS unit – Dyne
*One Newton = 10^5 dyne
*Strongest force in the universe
Ans:Nuclear force
*Weakest force in the universe
Ans:Gravitational Force
*Force acting for a short time
Ans:Impulsive force

CENTRIPETAL FORCE AND CENTRIFUGAL FORCE
CENTRIPETAL FORCE
*Force which acts on a body moving in a circular path and it is directed towards centre is called
Ans:Centripetal force
eg: Vehicle moving round a curved road requires this force
(when speed increases, more centripetal force is required)

CENTRIFUGAL FORCE
*Force that acts on a body moving in a circular path and is directed away from the centre is called
Ans:Centrifugal force
eg : This force helps to separate cream from milk
*Capability of rotating objects around a fixed axis is called
Ans:Torque
eg : Tightening of nut

FRICTIONAL FORCE
*Force that resists the movement of one surface over another is called
Ans:Frictional Force
*The substances which reduce the frictional force between moving surfaces
Ans:Lubricants
eg : Grease, Oil, Graphite etc.

APPLICATIONS OF FRICTION
*We can walk on ground
*Car can stop with a sudden brake
*Slow landing of a parachute through air

TYPES OF FRICTIONAL FORCES
*Static friction
Ans:Force acts in a direction opposite to the direction of motion
*Kinetic friction
Ans:Force occurs when two objects are moving relative to each other or rub together
*Rolling friction
Ans:Force acts when two bodies role one another
eg : Ball bearing operation

ADHESION FORCE
*Force of attraction between unlike molecules is termed as
Ans:Adhesion
eg : water drop sticks on glass surface

COHESION FORCE
*Force of attraction between like molecules is termed as
Ans:Cohesion
eg: water molecules join together

VISCOSITY
*Frictional force acting between parallel layers of a liquid is called
Ans : Viscosity
*Unit – Poise
*With increase in temperature, viscosity
Ans : Decreases
*Viscosity of gas is less than viscosity of
Ans : Liquid
*Viscosity of an ideal fluid is
Ans : Zero

MOBILE LIQUIDS
*Liquids having low viscosity are called
Ans : Mobile liquids
*Mobile liquids can flow easily
eg : Water, Kerosene, Alcohol, Petrol etc

SUPERFLUIDS
*Fluids flow with zero viscosity is called
Ans: Super fluids
*It shows antigravitational property
eg : Honey, Coal tar, Glycerine etc

SURFACE TENSION
*The property of a liquid by which the free surface of liquid acts like a stretched membrane
Ans : Surface tension
*Surface tension is caused due to
Ans : Unbalanced molecular cohesive force
*Surface tension is inversely proportional to temperature and
Ans : Pressure
*Surface tension of hot water is less than that of
Ans : Cold water

APPLICATIONS AND EXAMPLES
*Insects to walk over the water surface
*Spherical shape of rain drops
*Detergents inverse the surface tension of water

CAPILLARITY

• It is the phenomenon of surface tension
  eg : rise of water level in plants
  : The chalk and blotting paper quickly absorb ink
• It is due to adhesive force

ELASTICITY

• Ability of a body to return to its original shape is called
  Ans: Elasticity
• Hierarchy of elasticity
  Ans: Steel > Rubber

PRESSURE
*The force per unit area is called
Ans: Pressure
Pressure = Force/Area
*The SI Unit of pressure = Pascal or N/m2
*Unit of thrust
Ans : Newton
*CGS unit
Ans : dyne /cm2
*Force acts more on objects having
Ans : Low Surface area

ATMOSPHERIC PRESSURE
*Atmospheric pressure = 760mm of Mercury
*Unit of Atmospheric pressure
Ans : Bar
1 bar = 10^5 pascal
*Pressure at sea level is taken as the
Ans : Standard Atmospheric Pressure
*Barometer is used to calculate
Ans : Atmospheric Pressure
*The liquid used in Barometer
Ans : Mercury

BAROMETER
Liquid Level change Indication
*Rising-Calm climate
*Sudden fall-Storm

GRAVITATIONAL FORCE
*The mutual attractive force between two point masses m1 and m2, is inversely propotional to the square of the distance between them
Ans : Newton’s law of Gravitation
Fa^m1m2/d2 ->F=G^m1m2/d2
g -> gravitational constant
*Force of attraction between any two bodies in the universe is called
Ans : Gravitation
*Law of gravitation was discovered by
Ans : Sir Isaac Newton
*Weakest force in nature
Ans : Gravitational Force
*The force keeps the earth and other planetary objects in their orbits around the sun
Ans : Gravitational Force
*The acceleration with which the freely falling bodies are attracted towards the earth is called the
Ans : Acceleration due to gravity (g) g = 9.8m/s2 (32.2 feet/s2)
*Weight of freely falling body
Ans : Zero

VALUE OF’G’ IS
*Maximum at Polar regtons
*Minimum at Equatorial regions
*Zero at the center of the earth
*Universal Law of Gravitation was put forward by
Ans : Sir Isaac Newton
*The ‘g’ is maximum on Jupiter and minimum on the planet
Ans : Mercury
*Astronaut cannot drink lemonade with the help of a straw because
Ans : There is no atmosphere on the moon

ESCAPE VELOCITY
*Minimum speed which a body must have to escape from the earth’s gravitational force is called
Ans : Escape Velocity
*Escape velocity of moon
Ans : 2.4 km/s
*Escape velocity of earth
Ans : 11.2km/s
*Escape velocity of planet Jupiter
Ans : 60km/s
*Escape velocity of planet Mercury
Ans : 4.2km/s
*Escape velocity of the planets increases with its
Ans : Mass

LIGHT

• Scientific study of light
  Ans : Optics
• Light is an
  Ans : Electromagnetic Wave & Transverse wave
• It behaves as wave and particle. Thus light has dual nature
• Light travels through air or vacuum at a speed of
  Ans : 3 x 108m/s
  *Order of speed of light
  Ans : water < glass < air < vacuum
  *Velocity of light is greater than the
  Ans : Sound
  *Light reaches earth from sun in
  Ans : 8 minutes 20 seconds (500seconds)
  *Substances which do not pass light through them are called
  Ans : Opaque substances
  eg : paper, stone
  *Substances which allow light to’pass through them are called
  Ans : Transparent substances
  eg : glass
  *Wave theory of light was proposed by
  Ans : Christiaan Huygens
  *Electromagnetic theory of light was propsed by
  Ans : James Clark Maxwell
  *’The Corpuscular theory’ related to light was proposed by
  Ans : Isaac Newton in 1675
  *The shadow obtained from a point source is a region of darkness which is called
  Ans : Umbra

COLOURS
*Colour of any transparent object depends on the colour of the light transmitted by it
*Colour of any opaque object depends on the colour of light it reflects
*Spectrum of white light –
Ans : Light consits of seven colours such as Violet, indigo, Blue, Green Yellow, Orange and Red (VIBGYOR)
*The band of seven colours obtained due to the dispersion of white light is called
Ans : Visible Spectrum
*When frequency increases wave length
Ans : Decreases

• Deviation most through glass prism
  Ans : Red
• Deviation least through glass prism
  Ans : Violet
• Colour with maximum frequency
  Ans : Violet
• Colour with minimum wavelength
  Ans : Violet
• Colour with maximum wavelength
  Ans : Red
• Colour with minimum frequency
  Ans : Red
  *Colour used In laboratory for Indicating danger
  Ans : Yellow
  *Colour sensitive to human eye
  Ans : Yellow
  *Colour used as danger signal
  Ans : Red

DISCOVERIES SCIENTISTS
*Corpuscular theory – Isaac Newton
*Wave theory – Christiaan Huygens
*Quantum Theory – Max Planck
*Electromagnetic theory – James Clark Maxwell
*Photo electric effect – Heinrich Hertz
*A white surface reflects all form’s of light and heat
*A black surface absorbs all forms of light and heat
*Red light passing through a green object, appears
Ans : Black
*Sky appears blue – Due to the shorter wavelength of blue colour, it is scattered more than the red colour of longer wavelength

PRIMARY COLOURS AND IT’S COMBINATIONS
*Primary colours are
Ans : Red, Green, Blue
*Primary colours used in colour television are
Ans : Red, Green, Blue
*Colour television uses
Ans : Additive colour mixing
*By mixing suitable mixture of primary colours gives
Ans : Secondary colours
eg : Magenta, Cyan, Yellow
*Green Red = Yellow
*Blue Red = Magenta
*Green Blue = Cyan
*Green Blue Red = White
*The branch of physics which deals with the measurement of light emitted by objects is called
Ans : Photometry
*Tertiary colours:
Ans : Mixing up of two secondary colours

COMPLEMENTARY COLOURS:
Complementary colours are the primary colours which give white colour when put together with the secondary colours
*Green Magenta –>White
*Blue Yellow –>White
*Red Cyan –>White
*The substances used in colour paints, filters, plastics and other materials
Ans : Pigments
*Subtractive colour mixing is used in
Ans : Pigments
For printing, colour pigments used are
Ans : Yellow, Magenta, Cyan

QUANTUM THEORY
*The light rays consist of small energy packets called
Ans : Quantum
*Quantum of light is known as
Ans : Photon
*Quantum Theory was put forward by
Ans : Max Planck
*Absorption of light of one wave length by a substance and the re-emission of light of greater wavelength is called
Ans : Flourescence
*Emission of light in the visible region after absorbing certain electromagnetic radiations is called
Ans : Photoluminescence

PHOTOELECTRIC EFFECT
*Photoelectric Effect was proposed by
Ans : Heinrich Hertz
*Photoelectric Effect was explained by
Ans : Albert Einstein
*For his explanation of Photoelectric Effect, he got Nobel prize for Physics in
Ans : 1921
*Metal surfaces like Sodium, Potassium, Zinc will eject electrons when electromagnetic radiations fall upon them
*The Law of Photoelectric Effect was formulated by
Ans : Albert Einstein
*The working principle of solar cells
Ans : Photoelectric Effect

REFLECTION
*When a ray of light falls on a smooth surface and returns to the same medium, it is called
Ans : Reflection of light
*An object which reflects all colours appears as
Ans : White
*An object which absorbs all colours appears as
Ans : Black

REFRACTION
*The bending of light when a ray of light travels from one medium to another is called
Ans : Refraction
*Snell’s law is related with
Ans : Refraction

EXAMPLES FOR REFRACTION
*Twinkling of stars
*A pond looks shallow
*Stick appears to be bended, when immersed in water
*Early sunrise and late sunset
*Mirage

SNELL’S LAW
*The ratio of the sine of angle of incidence in the first medium to the sine of angle of refraction in the second medium is a constant for a given pair of medium and for a given wavelength of light
Ans : N – Sine i /Sine r
*Due to change of medium the phase velocity of the wave is changed but its frequency remains
Ans : Constant
*Fatamorgana is a term associated with
Ans : Mirage
*The measure of optical density of the medium is
Ans : Refractive index
*Refractive index of a medium
=Speed of light in vacuum /Speed of light in medium

REFRACTIVE INDEX
*Vacuum – 1
*Ice – 1.31
*Water – 1.33
*Diamond – 2.42

TOTAL INTERNAL REFLECTION
*The complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle is called
Ans : Total Internal Reflection
*The father of fibre optics
Ans : Narendra Singh Kapani

APPLICATIONS
In the construction of
*Optical fibres
*Endoscopy
*Vehicle reflectors
*Binoculars etc

EXAMPLES
*Sparkling of diamond
*Working principle of optical fibres
*Glittering of water bubbles

DISPERSION
*The splitting up of light ray into different colours is called
Ans : Dispersion
*Dispersion was discovered by
Ans : Sir Isaac Newton
*Rainbow is formed due to
Ans : Reflection, Refraction and Dispersion of light
*Main principle due to the formation of rainbow
Ans : Dispersion
*Rainbow is seen as circle from
Ans : Space
*Rainbow is seen as semi-circle from
Ans : Earth
*Rainbow appears in the opposite direction of
Ans : Light
*Red colour angle in rainbow
Ans : 42.8°
*Violet colour angle in rainbow
Ans : 40.8°
*Colour at top of a rainbow
Ans : Red
*Colour at bottom of a rainbow
Ans : Violet
*Colour at centre of a rainbow
Ans : Green

INTERFERENCE
*The phenomenon that occurs when two waves meet while travelling along the same medium
Ans : Interference
*Interference was observed first by
Ans : Thomas Young

APPLICATIONS AND EXAMPLES
*Different colour of the soap foam
*Oil spread in water
*Colours that appear on the upper layer of oil that spread on road
*Holography, Holograms

DIFFRACTION
*The bending of light around the corners of an obstacle or aperture into the region of geometrical shadow of the obstacle is called
Ans :Diffraction

APPLICATIONS AND EXAMPLES
*The fuzzy uneven edges of shadow
*Principle behind the working of projector in a film theatre
*Fringes pattern in CD

SCATTERING OF LIGHT
*The reflection of a ray from a straight path due to particles or in the interface between two media is called
Ans : Scattering of Light

EXAMPLES
*Reddening of sun at sunrise and sunset
*The blue colour of the sky and sea
*Colour lamp used in fog for veicles
Ans : Yellow light
*On moon, sky appears black colour due to the absence of
Ans : Scattering of light
*Rayleigh scattering
Ans : Due to this blue colour of the sky and yellow tone of the sun
*The scientist who explained the blue colour of the sky
Ans : Rayleigh
*The scientist who explained the blue colour of sea
Ans : C.V.Raman

TYNDAL EFFECT
*Scattering of light by colloidal particle is termed as
Ans : Tyndal effect

EXAMPLES
*Sunlight passing through the mist
*Twinkling of comet
*Blue colour seen in the smoke emitted by motor cycles

MIRRORS AND LENSES
*Spherical Mirrors are of
Ans : Two types
*Concave mirror
Ans: Reflecting surface curved inward
*Convex mirror
Ans : Reflecting surface curved outward

CONCAVE MIRROR CAN BE USED
*As a shaving mirror
*Reflector in solar cooker
*Reflector in astronomical telescope
*Search light and head light of automobiles
*Used by dentists and ENT specialists
*Used as burning glass
*Used in torches

CONVEX MIRROR CAN BE USED AS
*Rear view mirror in automobiles
*Device to check theft in shops
*The mirror forms a virtual or real image depending on the position of the object
Ans : Concave mirror

LENS
*A transparent medium bounded by two surfaces atleast one of which is curved surface is called
Ans: Lens
*The lens thicker at the middle than in edges is called
Ans: Convex Lens
*The lens thicker at edges than in the middle
Ans: Concave lens
*The unit of power of lens
Ans: Dioptre
*Power and focal length of convex lens
Ans: Positive
*The power and focal length of concave lens
Ans: Negative
*Lens in human eye
Ans: Convex lens
*Image formed in concave lens
Ans: Virtual and erect

ALTERNATIVE NAMES
*Converging lens – Convex lens
*Diverging fens – Concave lens
*Converging mirror – Concave mirror
*Diverging mirror – Convex mirror
*Image formed in Convex lens
Ans: Real and inverted
*The shortest distance for clear vision is
Ans: 25cm
*Twenty – Twenty means
Ans: Perfect vision

■ EYE RELATED DISORDERS AND THE LENSES USED
*Myopia/Shortsightendness
Can be corrected by using
Ans: Concave lens

• Hypermetropia / long sightedness
  Can be corrected by using
  Ans: Convex lens
  *Both Myopia and hypermetropia
  Can be corrected using
  Ans: bifocal lenses
  *Astigmatism
  Can be corrected by using
  Ans: cylindrical lens
  *Presbyopia
  Can be corrected by
  Ans: convex lenses

EXTRA POINTS
*Persistence of vision of human eye
Ans: 1/16 seconds
*Magnification
Ans: height of image / height of the real object
*Mirror equation = 1/u1/v=1/f

LASER
Fullform : Light Amplification by Stimulated Emission of Radiation
*LASER sources have only one type of wavelength
*LASER was discovered by
Ans : Theodore Maiman (1960)
*LASER is used in the medical field to perform minute operations
[w]
MASER
Fullform : Microwave Amplification by Stimulated Emission of Radiation
*MASER was discovered by
Charles.H.Towns

RADAR
Fullform : Radio Detection and Ranging
*Uses radiowaves to detect the position of objects such as missile, aeroplanes etc .
*RADAR was invented by
Ans : Albert.H.Taylorand Leo.C. Young

POLARISATION
*The phenomenon of confining the vibrations of a transverse to a particular direction is called
Ans : Polarisation
*Nicol prism is a Polaroid
*A natural polarizing material is
Ans : Tourmaline
*Brewster’s Law is associated with
Ans : Polarisation of Light

APPLICATIONS
*Used in windows of aeroplanes and cars
*Sunglasses
*3 dimensional motion pictures

DOPPLER EFFECT
*A change in frequency of light wave when the source or the observer moves with respect to one another is called
Ans : Doppler effect
*High pitch of the siren of an approaching ambulance which passes an observer is due to
Ans: Doppler effect
*Two types of shift occur due to this phenomenon
(1) Red Shift
Ans : Decrease in frequency of the visible light when it moves away from the observer
(2) Blue shift : Increase in frequency of the visible light when it moves towards the observer

ELECTROMAGNETIC RADIATION
*The pattern of arrangement of different types of electromagnetic radiations in the order of increasing wavelength
Ans : Electromagnetic spectrum
*Arrangement of radiations in the increasing order of wave length
Ans : Radiowaves > Microwaves > IR-rays > Visible light > UV rays > X – rays > Gama rays > Cosmic rays
*Maximum wavelength of electromagnetic wave
Ans : Radio waves
*Waves used for communication through satellite
Ans : Microwaves

X-RAYS
*Electromagnetic waves with shorter wavelength
Ans : X-rays
*Two types of X-rays
(1)Soft X-rays:
Having high wavelength and low energy used in radiations
(2)Hard X-rays:
Having short wavelength and high energy
*X-rays were Discovered by
Ans: Roentgen
*Rays used to study the internal atomic structure of crystal
Ans : X-rays
*Rays appear to be originated from outside of earth is called
Ans : Cosmic rays
*Cosmic rays was discovered by
Ans : Victor Hess

INFRARED RAYS (IR RAYS)
*Infrared Rays was discovered by
Ans : William Herschel
*Heat rays emitted by sun is
Ans : Infrared rays

USES AND EXAMPLES
*Infrared rays is used in TV remote
*Infrared rays is used in distant photography
*Heat of sun is due to
Ans : Infrared rays

ULTRAVIOLET RAYS (UV RAYS)
*The electromagnetic radiation with wavelength ranging from 10nm to 380nm
Ans : Ultraviolet Rays

APPLICATIONS
*For identifying the counterfeit currency
*Used to fill inside the tube lights
*Used to disinfect equipment used for operation
*It causes sunburn

WAVES
*The disturbance which propagates energy from one place to another without the transport of matter
Ans : Waves

TWO TYPES OF WAVES
*Longitudinal wave
*Transverse wave
*Particles vibrate parallel to the direction of propagation of wave
Ans : Longitudinal wave
eg : sound wave
*Particles vibrate perpendicular to the direction of propagation of wave
Ans : Transverse wave
eg : Light wave
*The distance between two successive crests or troughs
Ans : Wave length
*The maximum displacement of vibrating particle on either side from the equilibrium position
Ans: Amplitude
*The spatial frequency of a wave, either in cycles per unit distance or radians per unit distance is called
Ans: Wave Number
*Earthquake waves are
Ans: Infrasonic waves

SOUND
*A form of energy which produces sensation of hearing
Ans: Sound

• Sound requires a
  Ans: Medium to travel
• Sound cannot travel through
  Ans: Vacuum
• Study of sound is called
  Ans: Acoustics
• Velocity of sound in air
  Ans: 340m/s
• Velocity of sound is maximum in
  Ans: Solids
• Velocity of sound is least in
  Ans: Gases
• Sound has the maximum speed in
  Ans: Steel
• The number of oscillation made in one second is called
  Ans: Frequency
  Unit of frequency – Hertz (Hz)
  1 cycle/second -1 Hz
• Frequency of audible sound is
  Ans: 20Hz to 20,000 Hz
• The machine used to reproduce sound
  Ans: Phonogram
• The method of locating under water objects using sound waves
  Ans: SONAR (Sound Navigation and Ranging)
• Waves used in SONAR
  Ans: Ultrasonic waves
• The phenomena of sound which is used in stethoscope
  Ans: Reflection of sound
• The unit which is usually used to denote the intensity of pollution
  Ans: Parts per million (ppm)
• Normal sound level in decibel
  Ans: 60-120 db

FACTORS OF SOUND
(1)Pitch
(2)Loudness
(3)Timbre / Quality

PITCH
*The shrillness of sound felt by the ear
Ans: Pitch

LOUDNESS

• The intensity of sound is measured in » The intensity of sound felt by the ear
  Ans: Loudness

TIMBRE
*It is the quality of sound
*Different individuals have different Timbre

• Used to denote the speed of a supersonic plane
  Ans : Mach Number
• 1 Mach number is equal to
  Ans : 340 m/s
• Persistance of sound
  Ans : 1/10 seconds
• Velocity of sound in moist air is greater than in dry air
• Ultrasound scanning uses high frequency
  Ans : Ultrasonic waves

ECHO
*Echo and reverberation are due to the reflection of
Ans : Sound
*Minimum distance required for the production of echo
Ans : 17m
*Phenomenon utilized by bats to detect prey and obstacles in their path in night
Ans : Echolocation
*For echolocation bats use
Ans : Ultrasonic sound
*Depth of the sea is measured in
Ans : Fathom
1 fathom = 6 feet = 1.82 m

HEAT
*It is an indication of object’s internal energy or it is the degree of hotness/ coldness
Ans : Temperature
*Heat is measured in the unit of
Ans : Joule (J)
*The study of materials and phenomena at low temperature
Ans : Cryogenics

TEMPERATURE SCALES
*Celsius scale (C)
*Fahrenheit scale (F)
*Kelvin or absolute scale (K)
*Relationship of temperature scale
C/5 = F-32/9 = K-273/5
*In Kelvin scale there is no
Ans: Negative temperature
*The amount of heat required to raise the temperature of the substance through it
Ans: Heat capacity
*Calorie was the unit, formerly used to measure
Ans: Heat