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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-

369

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

372

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