Post on 22-Jan-2022
360
Physics
PhysicsMEASUREMENT & UNITS What is the unit of potential
difference ?
Volt Knot is used for measuring
Speed of ships
Unit of work
Joule Unit of viscosity of fluid
Poise
Decibel is the unit for measur-ing the intensity of
Sound
What is the S.I. unit of pressure?
Pascal
One angstrom is equal to
10-10m
How many Pascal is the atmo-spheric pressure ?
105 Pascal
What is the S.I. unit of magneticfield strength?
Ampere per metre
Which is the smallest unit of dis-tance used in Nuclear Physics?
Fermi
The unit used to measure radioactivity
Becquerel
What is the unit of frequency?
Hertz The power of the Engine is cal-
culated by
Horse Power (One HorsePower = 746 watt)
The unit of Capacitance
Farad
The unit of Inductance
Henry
The unit of atmospheric pres-sure
Bar (One Bar=76cm of Hg)
Unit of force
Newton Unit of Electric charge
Coloumb Unit of Electric resistance
Ohm
What is the use ofBarometer?
To measure the at-mospheric pressure
THE BASE UNITS OF SI UNITSParameter Unit Symbol
1. Length Metre m2. Mass Kilogram Kg3. Time Second s4. Electric current Ampere A5. Temperature Kelvin K6. Luminous intensity Candela cd7. Amount of substance mole mol
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Physics
The unit which is used to calcu-late the distance between theGalaxy
parsec (Parallactic second) The largest unit of distance
parsec (1parsec= 3×1013km) Electric power is measured by
Watt SI unit of temperature
Kelvin Unit of luminous intensity is
Candela The SI unit of wavelength of
light is
Angstrom The unit used to measure the
depth of the sea is
FathomOne fathom = 6 feet
The unit of distance in as-tronomy is
Light year The Unit of power of lens is
Dioptre
INSTRUMENTS AND ITSUSES
Which instrument convertsmechanical energy into electri-cal energy?
Dynamo Which instrument converts
light energy into electric en-ergy?
Photo electric cell
Which instrument used to con-vert A.C. current to D.C. cur-rent?
Rectifier
Which is the instrument em-ployed to change the voltage inan electric circuit?
Transformer
What is the use of Altimeter?
To measure the altitude What is the use of Ammeter?
To measure the flow of elec-tric current in a circuit
What is the use of Anemometer?
To measure the force orspeed of the wind
What is the use of Electroscope?
To measure the electrostaticcharge
What is the use of Calorimeter?
To measure the amount ofheat
What is the use of Speedometer?
To indicate the speed of avehicle
What is the use of Fathometer?
To measure the depth ofwater (1 fathom = 6 ft)
What is the use of Periscope?
To observe objects of thesurface from the submarine
What is the purpose ofMariner’s compass?
To find out the direction ofthe ship in the sea
What is the use of Steroscope?
To see the photos taken bytwo cameras placed at twodifferent angles
What is the use of Hygrometer?
To measure the humidity ofatmosphere.
What is the use of Galvanometer?
To measure electric currents What is the use of Microscope?
To magnify tiny objects What is Lactometer ?
device used to measure therelative density of milk todetermine its purity
The device that uses radiowaves to detect the position ofobjects such as Aeroplanes, mis-siles etc.
Radar What is Pyrometer ?
Used to record hightemperature from a greatdistance
What is Hydrophone ?
It is used for recording ofsound inside water
What is an electric oscillator ?
It converts Direct Currentinto Alternating Current
What is cyclotron ?
It is a device for producinghigh energy sub-atomic par-ticles
What is Geiger - Mullercounter?
It is used for detecting andmeasuring radio activeradiation
What is a nuclear reactor ?
It is the Central componentof a nuclear power station,which generates nuclearenergy under controlledconditions.
What is the use of Micro-phone?
A device used in soundreproduction systemsfor converting soundinto electrical energy.
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Physics
What is a hydrometer ?
It is used for measuring thedensity of liquids directly.
What is venturimeter ?
It is used for measuring flowof liquids
What is Radar ?
Radar is Radio Detectionand Ranging
WORK, POWER ANDENERGY
When a force acting on a bodyproduces displacement, it iscalled
Work
What is called the capacity todo work?
Energy Rate of doing work is called
Power1 horse power = 746 watt
Energy by virtue of which abody can do mechanical workis called
Mechanical Energy
Which are the two forms ofmechanical energy
Kinetic energy & Potentialenergy
The energy possessed by a bodybecause of its velocity is
Kinetic energy Kinetic energy is proportional
to
mass of the body & squareof its velocity
The energy possessed by a bodybecause of its position orchange in shape is called
Potential energy What happens to the potential
energy when the height of abody from the ground isdoubled?
Potential energy is alsodoubled
The energy possessed by thewater collected in the reservoirof a dam
potential energy
If the velocity of a body is in-creased, its kinetic energy
increases The SI Unit of
Work - joulepower - wattenergy - joule
Energy of one form can bechanged to another form. Theprocess is called
Energy Transformation What is the potential energy of
a body on the ground?
Zero Which is the main source of
energy to earth?
Sun
In the sun, which is convertedinto energy?
Matter What is called a device which
reduces human effort?
Machine What is called the ratio of the
resistance to the effort whenthey balance each other?
Mechanical advantage of asimple machine
What is called ‘lever’?
A rigid rod which can rotateabout a point fulcrum iscalled a lever.
What is first order lever?
In first order lever Fulcrumis between the resistance andeffort.
Write some examples of the firstorder levers:
Balance, scissors, spanner What is second order lever?
In second order lever resis-tance lies between the Ful-crum and effort
Write examples of second orderlever
Nut cracker, Wheel barrow,Bottle opener
Who proved the existenceof seven colours in sun-light?
Sir Isaac Newton
Who developed the lawof attraction or repul-sion of electric charges?
Coloumb
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Physics
What do you mean by the thirdorder lever?
The effort is in between theresistance and the fulcrum
Write examples of third orderlever
Fire tongs, forceps, ice tongs What changes is done in a dy-
namo?
Mechanical energy is con-verted into electrical energy.
What is the unit of work in theC.G.S. system?
Erg When a body falls freely work
is done by
Gravitational force One watt is equal to
One Joule / second “State the law of conservation
of energy”:
Energy can neither be cre-ated nor destroyed althoughit can be transformed fromone form to another
When is work always done ona body?
When it experience an in-crease in energy through amechanical influence
The unit of Speed and Velocityis
m/sec The unit of acceleration
metre/sec²
MOTION & FORCES A quantity which possess only
magnitude is called a
scalar quantity
Distance, Mass, Temperature,Time etc. are examples of whichquantity ?
Scalar quantity
A quantity which possess bothmagnitude and direction isknown as
Vector quantity
Examples of vector quanties are
(1) velocity
(2) acceleration
(3) force
(4) displacement
“If there is no external force, abody at rest continues to be atrest and a body in motion con-tinues to move with uniformvelocity”. This law is known as
The Law of Inertia
Who proposed the Law of Iner-tia ?
Galileo
Who proposed the Laws ofMotion ?
Isaac Newton
The distance travelled in unittime is called
speed
The distance travelled in unittime in a specific direction iscalled
velocity
Impulse of force
is the product of the forceand the time during whichthe force acts on the body.
The force acting for a very shorttime
impulsive force
The rate of change of velocityis called
acceleration
The kind of force that opposesrelative motion is known as
Friction
The rocket lift - off is based onwhich law ?
Newton’s 3rd Law ofMotion
The minimum speed which aspace craft needs to escapeearths gravitational force isknown as
escape speed (escape veloc-ity is wrong because speedis a scalar quantity)
The escape speed is
11.2 km/s or 7 miles /sec.
The SI unit of force is
Newton
Which force is needed to changethe direction of a movingbody?
External unbalanced
The momentum of a body de-pends on what?
Its mass and velocity
Why does the cotton wick in anoil-filled lamp keep on burn-ing?
In the cotton wick there areinnumerable capillaries inwhich oil continues to rise.
Speed = DistanceTime
Velocity = DisplacementTime
Acceleration = Change in VelocityTime
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Physics
The upward force which liquidact on bodies immersed in it iscalled
buoyant force
How does the rise of tempera-ture affect surface tension?
The surface tension de-creases with rise of tempera-ture.
An iron needle slowly placedon the surface of water floatson it because
of its surface tension A drop of oil is placed on the
surface of water. What will hap-pen to it?
It will spread as a thin layer Soap helps in cleaning the
clothes because:
It reduces the surface tensionof solution
If the diameter of capillary bedoubled, the rise of water incapillary will be
Half
When the distance between twobodies increases, the force be-tween them will
Decrease
The acceleration due to gravityis maximum at the
Poles The gravitational force on a
body placed at the centre of theearth will be
Zero The freely falling body appears
to be weightless. Why?
The force exerted by theearth is being used to accel-erate the body.
What is the force that opposesthe relative motion of two bod-ies that are in contact?
Friction
What is the ability of fluids tooffer resistance to flow?
Viscosity The frictional force offered by
a liquid is called
Viscous force Examples of viscous liquids
Glycerine, Castor oil, Coaltar and honey
Force of attraction betweenmolecules of the same kind iscalled
Force of cohesion Force of attraction between
molecules of different kinds iscalled
Force of adhesion The internal force developed
within a body when forces areapplied on it is called
Elastic force Is steel or rubber more elastic?
Steel is much more elasticthan rubber
The force between a magnetand a magnetic material or be-
tween two magnets is called
Magnetic force The path of the projectile is
called
trajectory
The trajectory of a projectilemoving under the influence ofa constant acceleration is a
Parabola
The projectile has maximumrange when the angle of pro-jection is
450
NEWTON’S LAW OFMOTION
Why does an athlete run somedistance before taking a longjump?
By running the atheletsgives himself larger inertiaof motion
What is Newton’s third law ofmotion?
To every action there is anequal and opposite reaction
The “theory of relativity” wasexplained by
Albert Einstein Albert Einstein got the Nobel
Prize for Physics in 1921 for ex-plaining
Photo Electric Effect The incapability of a body to
change by itself its state of restor its state of uniform motionalong a straight line
Inertia According to Newton’s third
law every force is accompaniedby an equal and opposite force.Then how can a movement takeplace?
Action and reaction act ondifferent bodies
The phenomenon of pho-toelectric effect was firstexplained by
Albert Einstein
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Physics
Swimming is possible on ac-count of
Third law of motion When we jump out of a boat
standing in water it moves
Backward A man is at rest in the middle
of a pond on perfectly smoothice. He can get himself to theshore by making use ofNewton’s
Third law A cannon after firing recoils
due to
Newton’s third law of motion Newton’s second law gives the
measure of
Force
PROPERTIES OF MATTER The ability of a solid to return
to its original shape, on the re-moval of the external force iscalled
Elasticity
If a solid does not regain itsoriginal shape and size, whenthe deforming force is re-moved, it is called
Plastic
Substances which can be elasti-cally stretched to large valuesof strain are called
elastomers
An elastomer in human body
Aorta
The mass per unit volume of asubstance is known as its
density
The ship entering from a riverin to sea rises up a little. Why ?
The density of a sea wateris higher than that of riverwater
An iron nail floats on mercurybut sinks in water, why ?
The specific density of ironis lower than that of mer-cury and higher that that ofwater
Clouds float in the atmospherebecause of their low.........
density
Whenever a body is immercedpartially or completely in afluid, it experiences an upwardforce. This is called,
buoyancy
Icebergs float in sea water be-cause the density of ice is
less than water
The shape of rain drop is spheri-cal due to
surface tension
The force of attraction betweenthe molecules of same materialis called
Cohesive force
The force of attraction betweenmolecules of two different ma-terial is called
adhesive force
The most characteristic prop-erty of liquid is
fluidity
Newton/metre² is the unit of
pressure
When salt is added to water, itssurface tension
increases
A body is floating in a liquid,the upthrust on the body is
equal to the weightdisplaced
The sudden fall of atmosphericpressure predicts
storm
Substances that reduces frictionare called
lubricants
HEAT & THERMODYNAMICS The heat energy required to
raise the temperature of onegram of water by 1°C is calledone
calorie
1 calorie equals
4.2 joules
The quantity of heat requiredto raise the temperature of unitmass of a substance by 1°C iscalled its
specific heat
Which liquid possess lowestspecific heat ?
Mercury
The temperature at which asolid substance gets convertedinto a liquid is called its
melting point (fusion point)
The temperature at which a liq-uid gets converted into vapourstate is called its
boiling point (vaporizationpoint)
The temperature at which thevapour gets converted into liq-uid is called
condensation point
The temperature at which a liq-uid gets converted into a solidis called
freezing point
The temperature which is equalin Fahrenheat Scale and KelvinScale
574.25k = 574.250 F
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Physics
The process in which a liquidchanges into its vapour from itssurface at a temperature belowits boiling point is called
evaporation
Specific heat of water is
4200J/Kg°C
The coolant used in car radia-tor is
water The transfer of heat between
different parts of the body orfrom one body to another incontact with it is called
conduction
The process of transfer of heatfrom one point of a fluid to an-other part of a fluid by themovement of fluid itself iscalled
convection
The transmission of heat fromone place to another withoutheating the medium is called
radiation
Solar energy is received by theearth through which process ?
Radiation
In a pressure cooker, cookingis faster because of .......
increased boiling point
Absolute zero is the tempera-ture at which
molecular motion stops
What do you mean by heat?
Heat is the agent which givesthe sensation of hotnessagainst coldness of the body
What is meant by the tempera-ture of a body?
It is the degree of hotness
What is boiling point?
It is the temperature atwhich a liquid boils
What is absolute zero?
It is the temperature atwhich the atoms of a sub-stance become stationary(-273°C or 0°K)
An ordinary clock loses time insummer. This is because:
the length of pendulumincreases and time perioddecreases
Sun rays reach on earth by
radiation
How does in a vacuum flask sil-vering reduce the loss of heat?
By radiation
In the celsius temperature scale,what is the absolute zero oftemperature?
-273.15°C
Why gas thermometers aremore sensitive than liquid ther-mometers?
Because gases expand morethan liquids
What happens when a bimetal-lic strip is heated?
It will bend towards themetal with lower thermalexpansion coefficient.
What is critical pressure?
It is the pressure required toliquefy a gas at the criticaltemperature
What is critical volume?
It is the volume occupied byone gram of gaseous sub-stance at critical temperatureand critical pressure
Which is dew point?
Temperature at which givenvolume of air becomes justsaturated with water vapouractually present in it.
Which produces more severeburns?
Steam Which factor is not needed to
calculate heat lost or gain whenthere is no change of state?
Relative density What is the maximum density
of water?
4°C Transfer of heat takesplace in
liquids and gases mostly by
convection The temperature which is equal
in celcius scale and Farenheatscale
-40
The surface of water in a lake isjust slowly being frozen. Whatis the temperature of water atthe bottom of the lake?
4°C Paraffin wax contracts on
solidication. What is the melt-ing point of wax?
Increase with pressure
Who propounded Ohm’slaw?
George Simon Ohm
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Physics
Alcohol is more volatile thanwater why?
Because its boiling point islower than water
The snow on the mountainsdoes not melt all at once whenit is heated by the sun. Why?
Because it has a high latentheat of fusion
What is an ideal gas?
Ideal gas is that which can-not be liquefied
The rate of transfer of heat ismaximum in
Radiation What happens when we go up
in the atmosphere?
The pressure decreases What is the lowest possible
temperature?
-273.16°C What is humidity?
The amount of water vapourin the air is termed as hu-midity
Which liquid is used in a ther-mometer?
Mercury
OPTICS The change in the direction of
light as it passes from one me-dium to another is called
refraction The phenomenon of splitting of
white light into seven coloursis known as
dispersion Rainbow is formed by
dispersion When light is dispersed, the
colour which is dispersed leastis
red
During dispersion, whichcolour shows maximum devia-tion ?
violet When light falls on an object, a
part of it is reflected in all di-rections. This process is called
scattering Light travels in a straight line.
This property is known as
rectilinear propagation oflight
Materials which transmit al-most all light rays throughthem are known as
Transparent Materials which transmit only
a small part of the light rays arecalled
Translucent
Materials which do not passlight through them are called
Opaque
All colours are reflected by a
white object
All colours are absorbed by a
black object
We see lightning first and hearthe thunder later because of
velocity of light is greaterthan the velocity of sound
The primary colours are
red, blue and green
Optical fibre works on the prin-ciple of
total internal reflection
The velocity of light is maxi-mum in
vacuum
If a flower illuminated by whitelight reflects red and bluecolours, the colour of the flowerwill be
Magenta
The splitting up of a compositelight into its component coloursis called
Dispersion
Dispersion occurs due to thedifference in
Wavelength
Any light which is composedof more than one colour isnamed as
Composite light
Irregular and partial reflectionof light during its passingthrough a medium is known as
Scattering
The colour produced by themixing of green and red is
Yellow
A green leaf appears green be-cause
it reflects green colour The beautiful colour of the soap
foam and oil spread water is dueto
interference of light
The phenomenon of natu-ral radioactivity was dis-covered by the scientist:
Henry M Becquerel
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Physics
How does a green leaf appearswhen it is viewed in a blue light?
Dark
The colour used in signal lampis
Red
The colour of the head lamp inmotor vehicles is
Yellow
The heat carried in the solarrays is
Infrared radiation
Sun burn is caused by whichradiation?
Ultraviolet At a place when green, red and
blue rays overlap, which colourwill be seen?White
The distribution of the compo-nent colours of a compositelight in the order of their wave-length or frequency as a resultof dispersion is called
Spectrum
When wavelength increases therate of scattering
Decreases The property of certain mate-
rial by virtue of which they ab-sorb light of shorter wavelengthand emit light of longer wave-length is called
Fluorescence
Why can we see pictures withnatural effect on a television?
Due to persistance of vision The colour of light obtained by
mixing of any two primarycolour of light is
Secondary colour
Whose theory is called theQuantum theory of light?
Max Planck’s theory
Why lightning is observed ear-lier than the thunder is heard?
Because light travels fasterthan sound
A photoelectric cell converts
Light energy into electricenergy
Tyndall effect is due to
Brownian Motion
If a surface absorbs all colours,it sees as
Black
If a surface reflects all colours,it sees as
White
Mirage is formed by
Refraction and total internalreflection
Why is the sky and sea blue incolour?
Due to the scattering of light
The formation of rainbow is dueto which phenomenon of light?
Refraction and dispersion
The colour seen on the outeredge of the rainbow is
Red
Which colour is obtained whenblue light and green light of thesame intensities are mixed to-gether?
Cyan The rays which appears to
originate outside the earth
the cosmic rays
In a doctor’s stethescope thesound is intensified because of
reflection of sound
When sunlight passes throughatmosphere, the colour whichscatters most is
Violet
What is called interference?
The modification of inten-sity in the region of super-imposition.
Who suggested the wavetheory of light?
Christian Huygens
What is the name of the scien-tist who suggested that the ve-locity of light is maximumwhile propagating throughvacuum?
Focault The intensity of light depends on
Amplitude
What is the reason for the for-mation if beautiful colours ona soap bubble or on a thin filmof oil when spread over water?
Interference
Who put forward the theory ofelectromagnetic radiation?
Maxwell Who discovered the photoelec-
tric effect?
Heinrich Hertz What is the velocity of light in
vacuum?
3 × 108 m/sec. Bending or spreading of light
around tiny opaque objects arecalled
Diffraction Which always reduces the ve-
locity of electromagneticwaves?
Medium
The unit of electromagnetic ra-
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Physics
diants having a certain wave-length and a definite amount ofenergy is
Photon
What is directly proportional tothe energy of a photon?
Frequency
Shadows have fuzzy unevenedges because of
Diffraction
Newton postulated his corpus-cular theory of light on the ba-sis of
Rectilinear propagation oflight
OPTICAL INSTRUMENTS How is the temperature of the
sun measured?
Pyrometer The magnifying power of a
simple microscope can be in-creased if we use eye piece of
Smaller focal length Large aperture of telescope are
used for
Greater resolution The image of a distant object as
seen through an astronomicaltelescope is
Inverted
For the rear view, motorists use
convex mirror
A man cannot see objects dis-tinctly at a distance less than onemetre. He is suffering from
Hypermetropia
The disease of astigmatism inhuman eye is because of
Unequal and uneven curva-ture of eye lens
The ability of eye to focus thenear as well as distant object iscalled
Power of accommodation
To remove hypermetropia lensused is
Convex
A short sighted person usesspectacles fitted with
Concave lenses
A cylindrical lens is requiredto correct
Astigmatism The shortest distance of clear
vision is
25cm
The lens in the human eye
convex
CURRENT ELECTRICITYAND ELECTRONICS
Flow of electrically chargedparticles is
Electric current
Charge flowing in one seond
Intensity of electric current Any substance which can offer
resistance to the flow of elec-trons is called a
Resistor Name the instrument that con-
verts electrical signals intosound signals
Loud Speaker Which instrument is used to
change the direction of the flowof current
Commutator What is the voltage in house
supplyline?
230 volts (AC) Which is the principal element
used in the production of solarcell?
Silicon Which instrument converts elec-
trical energy into light energy?
Electric lamp Which instrument converts
electrical energy into mechani-cal energy?
Electric motor What is the unit used to mea-
sure electro motive force?
Volt
Which is the commercial unitof electric power?
k.w.h Which instrument converts
sound into electricity?
Microphone
A man cannotsee objectsdistinctly at adistancegreater than 3metres. He issufferingfrom
Myopia
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Physics
A high current produced in alow resistance circuit when twowires of main comes in contactwith each other is called
short circuiting
The frequency of household acin India
50 hertz
Which part on the refrigeratorcontrols the temperature level?
Thermostat
Which battery is used in vehicles?
Storage battery
Tangent galvanometer mea-sures
Current
The best instrument for the ac-curate measurement of the EMFof a cell is
Potentiometer
The resistance of an ideal voltmeter is
Infinite
Short circuit means
Direct flow of current be-tween points of the samepotentials
Best conductor of electricity is
Silver
The principle on which a quartzcrystal in a watch works
Piezoelectricity
The thickness of certain ceram-ics changes when a voltage isapplied across them this prop-erty is called
Piezoelectricity
A small piece of wire madefrom an alloy of lead and tin isused to avoid overloading is
Fuse
Nichrome is used in the manu-facture of heating elements dueto its
High resistance
Device which converts me-chanical energy into electricalenergy
Dynamo, It works on theprinciple of electro mag-netic induction
Diode valves can be used as
A rectifier
A device which can store con-siderable amount of charge iscalled
Condenser or capacitor The battery used in mobile
phone ?
Lithium ion battery
Which cell is used in watch ?
Button cell (mercury cell)
Which is the weakest kind ofbonding in solids?
Vander Waal’s In good conductors of electric-
ity, which type of bonding ex-ists?
Metallic The conductivity of a intrinsic
semi conductor at absolute zero is
Zero
A transformer is used
increase or decrease A.C.voltage
Any material that allows thepassage of electricity and heatis called?
Conductor In artificial satellites, electric
current is supplied by
Solar cells When a tape recorder operates
Magnetic energy is con-verted into sound energy
Energy stored in the dry cells is
Electrical Father of electricity
Michael Faraday Potential difference in an elec-
tric circuit is measured by
voltmeter The current in an electrical cir-
cuit is measured by
ammeter The instrument used to detect
the presence and direction offlow of current is called
galvanometer The property by which a con-
ductor opposes the flow of electriccurrent through it, is known as
resistance Electric current is the flow of
electrons The colour of earth wire is gen-
erally
green The filament of an electric bulb
is made up of tungsten becauseit possess
high melting point andresistance
Fuse wire is made up of
Tin and Lead (solder)
SI Unit of1) potential difference - volt
2) current - ampere3) electric power - watt
4) resistance - ohms
5) Angle - Radian
6) Wave length - metre7) Weight - Newton
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Physics
When large current passesthrough the fuse wire, it meltsaway. Why ?
Due to the low meltingpoint of tin - lead alloy
A device used instead of fuse ?
MCB (Miniature CircuitBreaker - It works on thePrinciple of magnetic effectof electric current)
What is the unit of intensity ofMagnetic field ?
Tesla
Rubber, plastic, paper, glass,mica etc. are electrical ...........
insulators
Power of an ordinary torch cellis
1.5 volt
Magnetic effect of electric cur-rent was discovered by
Oersted
The law of electromagnetic in-duction have been used in theconstruction of a
generator Which instrument is used to
measure magnetic field
Fluxmeter The device used for converting
current from a lower voltageto a higher voltage is known as
transformer What is electronics?
Study of behaviour ofelectrons, their control & use
A material which allows only afeeble current to pass throughit are called
Semiconductors The process of adding certain
impurities in the crystal struc-ture of a semiconductor so as toimprove its conductivity is called
Doping
The process of allowing electriccurrent to flow in one directiononly is
Rectification
What is Detection?
The process of extractingaudio signals from the highfrequency carrier waves isdetection
Which device converts alternat-ing current (AC) to direct cur-rent (DC)
Rectifier
Which device convert DC to AC
Electric oscillator
‘IC’ chip for computers are usu-ally made of
silicon
The common constituent oftransistor is
germanium
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Physics
SOUND What is a sound?
Sound is a form of energywhich produces the sensa-tion of hearing
Sound waves are
longitudinal waves
The Unit of loudness is
Decibel
The unit of intensity of light
Lambert
Sounds with frequencies lowerthan the lowest limit of humanhearing are called
infrasonic waves
Sounds with frequency higherthan 20,000 Hz are known as
ultrasonic waves
The audible frequency of hu-man ear
Between 20 hertz & 20,000hertz
Sounds are distinguished fromeach other by
pitch (frequency) loudness(intensity) and quality
Which waves are used in mo-bile phone ?
Micro waves
How is the sound produced?
By the vibration of materialbody
What is frequency of sound?
The number of vibrationsmade by a body in one sec-ond is called its frequency
Bat can fly at night because itproduces
Ultrasonic sound The distance travelled by a
wave during the time a particleof the medium makes one vi-
bration is called
Wave length The distance travelled by a
wave in one second
Velocity of the wave What are sound waves?
Longitudinal waves A wave motion in which the
particles of the medium vibrateparallel to the direction ofpropagation of wave is
Longitudinal The reflected sound is called
Echo The apparatus used for measur-
ing the depth of the sea on thebasis of echo is called
sonar How is the sound produced
when we speak?
By the vibration of vocal cords Which sound is produced by
Galton whistle?
Ultrasonic
When a harmonium is played,how is the sound produced?
By the vibration of the reeds
What is required for the propa-gation of sound?
Medium
When the frequency of thesound wave is increased, whathappens to its wave length?
Decreased Which unit is used to measure
the frequency of sound?
Hertz
Normal level of sound is
60-120 dB The maximum displacement of
the particles of the mediumfrom their equilibrium posi-tion?
Amplitude How is Echo produced?
By the reflection of sound A wave in which particles of the
medium vibrate perpendicularto the direction of propagationof the wave is
Transverse wave How is the speed of supersonic
plane expressed?
Mach number Supersonic plane fly with the
speed
Greater than the speed ofsound
When will the sound be pain-ful to the ears?
When the sound is above 120dB
What are the essential charac-teristics of a wave?
Wave length, amplitude,frequency and velocity
What is known as the study ofsound?
Acoustics
GALILEO GALILEI(1564 - 1642)
Born in Pisa, in Italy. He wasa key figure in the scientificrevolution in Europe. Heinvented the concept of ac-celeration; proposed the lawof inertia and his discover-ies in astronomy wereequally revolutionary manyregards Galileo as the “Fa-ther of Modern Science”.
373
Physics
Which property of sound is af-fected by change in air tem-perature?
Wavelength Which property of a wave is
independent of the other?
Amplitude Why an astronaut can’t hear his
companion at the surface of themoon?
There is no medium forsound propagation
Ultrasonic waves are produced by
Piezo electric effect When mechanical waves have
a frequency below the audiblerange it is known as
Infrasonics Which wave are used in
sonography?
Ultrasonic When mechanical waves have
a frequency above the audiblerange it is known as
Ultrasonics What is the velocity of sound
in air?
300 m/s In which medium the velocity
of sound is maximum?
Steel What is the velocity of sound
in vacuum (in m/s)?
0 With the rise in temperature,
velocity of sound
Increases The velocity of sound in any gas
depends upon its
Density and Elasticity
NUCLEAR PHYSICS The maximum penetrating
power is that of
- rays
The energy produced in anuclear reactor is on account of
nuclear fission
The age of rocks and fossils canbe calculated through
carbon dating
The first man made element is
Technitium
Which element is usually usedin radiation theraphy ?
Cobalt - 60
The first atomic reactor inIndia is
Apsara (Maharashtra -Trombay)
India’s first fast breeder reactoris at
Kalpakkom in Tamilnadu
In the interior of the sun, whichreaction takes place?
Nuclear fusion In the core of the sun, hydro-
gen nuclei fuse together to formwhich nuclei?
Helium The radiation which is not af-
fected by the magnetic field orelectric field is
rays
A metal which can absorb andstop radioactive radiations:
Lead
When a nucleus emits a betaparticle its atomic number:
Increases by one
When a nucleus emits a betaparticle it always emits
Anti neutrino
Which is the element with thegreatest half life period
Urnanium - 238
Artificial radioactivity was firstdiscovered by
Irene Joliot Curie andFrederic Joliot
The radiations which can penetratemost through substances are
Gamma rays
The radio isotope formed in theatmosphere due to the action ofcosmic rays is
Carbon 14
An isotope which is used in theproduction of radio pharmaceu-tical substance is
Oxygen 15 When an alpha particle is emit-
ted the atomic number of isotope
Decreases by two When a nucleus emits a beta
particle the mass number ofatom
Remains the same The half life period of Carbon
14 is:
5760 years Reactions involving changes in
the nucleus are called
Nuclear energy Pitch blende is the ore of
Uranium
BALLAST TANKSThese are large tanks
found in submarines. Whena submarine is to be sub-merged, these tanks are filledwith sea water. This increasesthe total weight of the vesseland its sinks. To make it riseto the surface, compressed airis pumped into the tankswhich forces the water out.The weight of submarine de-creases and rises to the sur-face.
374
Physics
Which radiation exhibit high-est ionizing power
Alpha rays The scientist who showed that
radioactive isotope may giveoff three types of radiation was
Rutherford Alpha particle is the nucleus of
which atom?
Helium Beta rays are emitted by the
atom from
The neutron of its nucleus The first product formed in Ura-
nium 238 disintegration seriesis
Thorium - 234 Isotones differ only in the num-
ber of
Neutrons Beta rays are a stream of
Electrons A particle similar to electron
carrying positive charge iscalled
Positron
What is Nuclear fission?
The process of splitting thenuclei of heavy atoms intotwo approximately equalmasses
What is Nuclear reactor?
Nuclear reactor is a deviceused to produce nuclear en-ergy by controlled nuclearfission
What is Moderator?
It is the substance used toslow down the fast neutronsin a nuclear reactor
Write examples of Moderators:
Graphite and heavy water
What are control rods?
It is made of substancewhich can absorb neutronsand control the rate of chainreaction
The most suitable particle forsplitting the nucleus of an atom is
Neutron
The substances used to absorbneutrons are
Cadmium or boron rods
The minimum mass of a radioactive substance required tosustain chain reaction is calledits
Critical mass
The process of repeated fissionof the remaining fissionableatoms by the neutrons pro-duced by earlier fission is called
Chain reaction
INVENTION Photoelectric effect, Theory of
Relativity etc. were discoveredby
Albert Einstein
Pressure cooker was inventedby
Denis Papin
Electric bulb was invented byThomas Alva Edison who isknown as
“Wizard of Menlo Park”
Tachyons are the particleswhich travel faster than light.They are invented by a Keralite
E.C.G. Sudarshan
John Barden, Walter H. Barttainand William Shockley are thescientists who invented
Transistor
Laser was invented by
Theodore H. Maiman
“Radar” was invented by
Albert H. Taylor and Leo C.Young
Dynamite and Gun Pow-der were invented by thefounder of Nobel Prize
Alfred Nobel
375
Physics
Who invented “Clinical Ther-mometer”
Thomas Cliford Albert
Father of Atom bomb is
Robert Oppenheimer
Who discovered nuclear fission
Otto Hahn
“Father of Hydrogen Bomb”
Edward Teller Who first made an electromag-
net?
William Sturger
X-ray was invented by
Wilhelm K Roentgen Who discovered the existence
of the nucleus inside the atom?
Rutherford - in 1911 Who propounded the theory of
electrolysis?
Faraday Who discovered Battery (elec-
tric)?
Alessandro volta Who discovered superconduc-
tivity?
Cammerling Onnes
MISCELLANEOUS What is called stress?
The restoring force per unitarea set up inside the bodyis called stress
What is the unit of stress?
C.G.S. system-dyne/cm2,M.K.S. system-newton / m2
Which substance has the high-est elasticity?
Steel What is the escape speed from
the moon?
2.37 km / sec. Which is the direction of rota-
tion of a synchronous satelliteof earth?
West to east
A particular star has mass twicethat of sun. This star will endup eventually as a
Black hole
The escape velocity of a projectilefrom the earth is approximately
11.2 km / sec.
As we go from the equator tothe poles, value of ‘g’
increases
The weight of a body at the cen-tre of the earth is
Zero
Weightlessness experiencedwhile orbiting the earth in spaceships is the result of
Acceleration
To an astronaut in a spaceshipthe sky appears black due to
Absence of atmosphere in itsneighbourhood
The value of ‘g’ on equator is
Minimum
Persons sitting in artificial sat-ellite of the earth have
Zero weight
The period of geo-stationaryartificial satellite of the earth is
24 hrs.
Who invented DieselEngine?
Rudolf Diesel
376
Physics
The atmosphere is held to theearth by
Gravity What is thermoplastic?
A substance which softenson heating and hardens on -cooling
Where does the water in a res-ervoir exert pressure?
In all direction Which quantity has direction as
well as magnitude?
Vector quantity What is the branch of science
concerning the study of bodiesin motion?
Kinetics The rays that come from sun
and other stars are called
Cosmic rays Sun and other stars exist in the
state of
Plasma It is difficult to cook at high al-
titudes because of
Decrease in boiling point ofwater
If the door of a refrigerator iskept open with the main sup-ply, the temperature of theroom
Increases Hygrometer is used for measur-
ing
Amount of water vapour in air A cold bottle is taken from a
refrigerator and weighed. Astime progresses we will find
the bottle slightly gainsweight
Which has the shortest wave-length?
ray Which has the longest wave-
length?
Radio waves
Which waves are used for tele-communication through artifi-cial satellites?
Microwaves Which electromagnetic wave
has the highest frequency?
ray What increases with the in-
crease of the penetrating powerof X-rays?
Frequency What are X-rays?
They are electromagneticradiation
A simple pendulum is set upinside a lift. The period of os-cillations is maximum when thelift is:
Moving downward with ac-celeration
How will the period of oscilla-tion of simple pendulum be af-fected if it is moved from thesurface of earth to a mine
It will increase Two bullets are fired horizon-
tally with different velocitiesfrom the same height. Whichwill reach the ground first?
Both will reach simulta-neously
A particle moves in a plane witha constant acceleration in a di-rection different from the ini-tial velocity. The path of theparticle is
Parabola
Material which is repelled fee-bly by a magnet
diamagnetic material
Material which is attracted fee-bly by a magnet
Paramagnetic
Electric motor converts
Electrical energy into me-chanical energy
The shape of rain drop is spheri-cal due to
surface tension
Magnetism at the centre of thebar magnet is
zero
Fuses are connected in ......... tothe live wire
series
When seen in blue light a redrose will appear as
black
A steam engine convert heatenergy into
mechanical energy
A person climbing a hill bendsforward inorder to
increase stability
Winding a watch is actually theprocess of storing
potential energy
Pitch of a sound depends uponits
frequency