luminous intensity

8/17/2019 Luminous Intensity

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Luminous Intensity Candela Cd Amount of substance Mol mol

two supplementary units are also defined, viz., radian[rad] for plane angleand steradian(sr ) for solid angle.

Force yne !ewton "!ewton#"$%dyne

&or' erg (oule " (oule# "$erg

Length Mass Time

Lig*t year# distancetraveled by lig*t inone year in vaccum ." Ly # +.-"$"%m" /arsec# 0.1-ly#1.$-"$"-m" !autical mile or seamile #-$1$ ft." micron # "2m #"$3-m." Angestron 4A$) #"$3"%m.

" 5uintol # "$1'g" Metric ton #"$0'g" Atomic massunit4amu) or dalton#".--"$31'g"6lug #".%+ 'g" /ound # $.%0 'g" C*andras*e'*ar limit # ". times t*emass of t*e 6un# 1.7"$0$'g.

" 6olar year # 7-$$seconds." year 0-%81 solar days." Lunar mont* #1.0solar daysTropical year # It ist*e year in w*ic* totalsolar eclipse occurs.Leap year # It is t*eyear in w*ic* t*emont* of February isof 1+ days.

Prefx Name Symbol Power-o-Ten

yocto y 10-24

zepto z 10-21

atto a 10-18

femto f 10-15


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pico p 10-12

nano ! 10-9

micro µ 10-6

milli M 10-3

centi C 10-2

deci 10-1

9unity: 9none: 100

de'a da 10+1

*ecto ; 10+2

'ilo < 10+3

mega M 10+6

giga = 10+9

tera > 10+12

peta / 10+15e?a @ 10+18

zetta 10+21

yotta B 10+24

Mass, 6peed, wor', volume, time, power, energy etc. are scalars

isplacement, velocity, acceleration, force, momentum,impulse, torue etc.vecotrs

@lectric current t*oug* *ave direction, is a scalar uantity because it doesnot obey t*e triangle law.Moment of inertia, pressure, reflective inde?, and stress are tensor uantities.

isplacement may be positive, negative or zero but distance is alwayspositive.DIn general magnitude of displacement E distance.


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work done due to displacement caused by a force is a scalar quantity.>*e dot product of vector quantities is always scalarwork done due todisplacement caused by a force is ascalar quantity. >*e dot productof vector quantities is always scalar

Force and displacement are vector quantities 4t*ey *ave bot* magnitudeand direction) and t*e dot product of two vector uantites always givesa scalar quantity.

@nergy scalar

Potential Energy: >*e capacity of doing wor' developed in a body due to

its position or configuration is called its potential energy. Example:4i)

@nergy of stretc*ed or compressed spring4ii)

@nergy of water collected at a *eig*t4iii)

@nergy of spring in a watc*.


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ynamoMec*anical energy into electrical energy

elation !etween Momentum and "inetic Energy

"#E $ P% &%m where p$ momentum $ mv

&s. &*, 'w* are units of wor' and energy.

1 watt hour = 3600 Joule

1 kilowatt hour = 3.6 x 10^6 joule

1HP = 746 watt'ome eamples o) inertia:

4i)

&*en a car or a train starts suddenly, t*e passengers bendsbac'ward.

4ii)

&*en a running *orse stops suddenly, t*e rider bends forward.4iii)

&*en a coat8 blan'et beaten by a stic', t*e dust particles are removed

Principal o) conservation o) linear momentum: If no e?ternal force actson a system of bodies, t*e total linear momentum of t*e system of bodiesremains constant. As a conseuence, t*e total momentum of bodies after and beforecollision remains t*e same. Eg !oc"et

*ewton+s third law o) motion: >o every action, t*ere is an opposite andeual reaction. Examples of third law:

(i)

ecoil of a gun(ii)

Motion of a roc'et(iii)

6wimming(iv)

&*ile drawing water from t*e well, if t*e string brea's up t*en mandrawing water falls bac'.


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*ewton,s Law o) -ravitation: >*e force of gravitational attractionbetween two point of bodies is directly proportional to t*eir mass andinversely proportional to t*e suire of t*e distance between t*em

G is appro?imately eual to -.-G"$H"" ! m1 'gH1

#ccele!at$o% &ue to g!a'$ty $( $%&e)e%&e%t o* (a)e, ($e a%&a(( o* te /o&y.

E(ca)e 'eloc$ty at te Moon's (u!*ace $( 2. km!s.

low e(ca)e 'eloc$ty te!e $( %o ato()e!e o% te oo%

alue o* g &ec!ea(e( w$t e$gt o! &e)t *!o Ea!t (u!*ace.

g $( ax$u at "oles.

g $( $%$u at e#uator.g &ec!ea(e( &ue to rotation o $arth

g &ec!ea(e( $* a%gula! ()ee& o* Ea!t $%c!ea(e( . .ngular speed is t*erate at w*ic* an obect c*anges its angle 4measured) in radians.

If t*e angular speed of t*e eart* becomes " times its present value, t*ebody present on t*e euator weig*tless.

/eight o) a !ody in a li)t:(i0

If lift is stationary or moving wit* uniform speed 4eit*er upward or downward), t*e apparent weig*t of body is eual to its true weig*t.

(ii0

If lift is going upward t*en apparent weig*t of a body is more t*an t*etrue weig*t.

(iii0

If lift is going downward t*en apparent weig*t of a body is less t*ant*e true weig*t.

(iv0

If t*e cord of t*e lift is bro'en, it falls freely. In t*is situation t*e weig*tof a body in t*e lift becomes zero. >*is is t*e situation of weig*tlessness.

(v0

&*ile going down, if t*e acceleration of t*e lift is more t*an t*eacceleration due to gravity, a body in t*e lift goes in t*e contact of t*eceiling of lift.


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"epler+s Laws o) planetary motion:4i)

All planets move around t*e sun in elliptical orbits, wit* t*e sun beingat rest at one focus of t*e orbit.

4ii)

>*e position vector of t*e planet wit* sun at t*e origin sweeps outeual area in eual time i.e. t*e areal velocity of planet around t*e sunalways remains constant.

A conseuence of t*is law is t*at t*e speed of planet increases w*ent*e planet is closer to t*e sun and decreases w*en t*e planet is far awayfrom t*e sun. 6peed of a planet is ma?imum w*en it is at perigee andminimum w*en it is at apogee.

4iii)

>*e suare of t*e period of revolution of a planet around t*e sun isdirectly proportional to t*e cube of mean distance of t*e planet from t*esun.

If > is period of revolution and r is t*e mean distance of planet from t*e

sun, t*en T% 1 r 2. Clearly distant planets *ave larger period of revolution. >*e timeperiod of nearest

planet Mercury is 77 days, w*ere as time period of fart*est planet/luto is 1. years.

Jrbital speed of a satellite is independent of its mass. ;ence satellites of differentmasses revolving in t*e orbit of same radius *ave same orbital speed.

4ii)

Jrbital speed of a satellite depends upon t*e radius of orbit 4;eig*t of t*e orbit from t*e surface of t*e eart*). =reater t*e radius of orbit lesser willbe t*e orbital speed.D >*e orbital speed of satellite revolving near t*e surface of eart* is .+'m8sec.

period of revolution # circumference of orbit 8 orbital speedK

/eriod of revolution of a satellite depends upon t*e *eig*t of satellite from t*esurface of t*e eart*. =reater t*e *eig*ts more will be t*e period of revolution.

4ii)

/eriod of revolution of a satellite is independent of its mass.D >*e period of revolution of satellite near t*e surface of t*e eart* is "*our 1 minute 47 minute).


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-eo3'tationary 'atellite: If a satellite revolves in a euatorial plane in t*edirection of t*e eart* rotation i.e. from west to east wit* a period of revolution eual to time period of rotation of eart* on its own a?is i.e. 1*ours, t*en satellite will appear stationary relative to eart*. 6uc* a satelliteis called =eo36tationary 6atellite. 6uc* a satellite revolves around t*e eart*at a *eig*t of 0-$$$ 'm. >*e orbit of =eo36tationary satellite is calledpar'ing orbit. Art*er C. Clarc' was t*e first to predict t*at a communicationsatellite can be stationed in t*e geosync*ronous orbit.

%eo-stationary satellite is use& to teleca(t. )!og!ae(*!o o%e )a!t o* te wo!l& to a%ote! weate! *o!eca(t$%g, $%)!e&$ct$o%( o* oo&( a%& &!ougt(.

$e )e!$o& o* !otat$o% o* geo-(tat$o%a!y (atell$te $( 24 .

eo-(tat$o%a!y (atell$te !e'ol'e( a!ou%& te Ea!t at a e$gt36000 " a))!ox.

ola! atell$te e'ol'e( a!ou%& te ea!t $% )ola! o!/$t at a e$gto* ((km a)). $e )e!$o&( o* te(e (atell$te( $( min.

a polar satellite is a satellite t*at travels around t*e eart* passing over bot* poles wit* every orbit. Polar orbits are often used for eart*3mapping,

eart* observation, capturing t*e eart*Escape 4elocity: @scape velocity is t*at minimum velocity wit* w*ic* abody s*ould be proected from t*e surface of t*e eart* so as it goes out of t*e gravitational field of t*e eart* and never returns to t*e eart*.D @scape velocity is independent of mass, s*ape and size of t*e body andits direction of proection.D @scape velocity is also called second cosmic velocity.D For eart* escape velocity # "".1 'm8sec. For moon escape velocity # 1. 'm8sec.

D Jrbital speed of satellite 45 $ 6g and escape velocity 4e$ 6%g&*ere is t*e radius of eart* i.e. 4e$ 6% 45 i.e escape velocity is 1 timest*e orbital velocity.>*erefore if orbital velocity of a satellite is increased 1 times 4increased by"), t*en t*e satellite will leave t*e orbit and escape


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e accele!at$o% &ue to g!a'$ty at te oo% $( one-sixth tat o* te Ea!t. o, te we$gt o* a )e!(o% o% te (u!*ace o* te oo%w$ll /e 1!) o* $( actual we$gt o% te Ea!t.

e Ea!t !otate( o% $t( ax$( *!o *est to $ast. $( !otat$o%a"e( te u% a%& te (ta!( a))ea! to /e o'$%g ac!o(( te ("y*!o $ast to *est

e )e!$o& o* !e'olut$o% o* (atell$te !e'ol'$%g %ea! te (u!*ace o* ea!t $( 1 ou! 24 $%ute(

;eat is t*at form of energy w*ic* flows from one body to ot*er body due todifference in temperature between t*e bodied. >*e amount of *eat

contained in a body depends upon t*e mass of t*e body.

if ."7- oule of wor' is performed, " calorie of *eat is consumed.

7#-#' 8nit: 7alorie $ It is amount of *eat reuired to raise temperature of " g of pure water t*roug* "oC.9nternational 7alorie: It is amount of *eat reuired to raise temperature of " g of pure water from ".%oC to "%.%oC.

P' 8nit: N.>*.O. 4 Nritis* >*ermal Onit) # It is amount of *eat reuired toraise t*e temperature of " pound of pure water t*roug* "oF.

" N.>*.O. # 1%1 calorie " calorie # ."7- oule" >*erm # "$% N.>*.O. " pound calorie # %0.- calorie

Freezing point of mercury is 30+oC.

measure temperature below t*is temperature, alco*ol t*ermometer isused. F./. of alco*ol is 3""%oC.

Mercury Thermometer: from 0$oC to 0%$oC

Pyrometer: &*en a body is at *ig* temperature, it glows brig*tly and t*e


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radiation emitted by t*e body is directly proportional to t*e fourt* power of absolute temperature of t*e body. adiation pyrometer measures t*etemperature of a body by measuring t*e radiation emitted by t*e body. >*is t*ermometer is not put in contact wit* t*e body. Nut it can notmeasure temperature below 7$$PC because at low temperature emissionof radiation is very small and can not be detected.

6pecific *eat capacity of a material is t*e amount of *eat reuired to raiset*e temperature of unit mass of substance t*roug* "P. Its 6I unit is oule 8'ilogram


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Anomalous e?pansion of water T Almost every liuid e?pands wit* t*eincrease in temperature. Nut w*en temperature of water is increased from

$PC to PC, its volume decreases. If t*e temperature isU increased abovePC, its volume starts increasing. Clearly density of water is ma?imum atPC

@art*Vs atmosp*ere is *eated by convection.

6atellitte is *eated by radiation

adiation : In t*is met*od transfer of *eat ta'es place wit* t*e speed of lig*t wit*out affecting t*e intervening medium due to @lectromagnetic

wavesW

!ig*ts are cooler in deserts t*an plains..because sand radiates more *eat

Clear nig*ts are cooler t*an cloudy because of radiation

*ewton,s law o) cooling : >*e rate of loss of *eat by a body is directlyproportional to t*e difference in temperature between t*e body and t*esurrounding. Convenction

*ewton,s Law o) 7ooling;# states t*at t*e *otter an obect is, t*e faster itcools.

;ollow sp*ere, cube, circular plateXsame material, *eated upt o sametempWsp*ere cools fast..more surface area

adiator Yconvenction

>empXavg 'inetic enegy of molecule.


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usion : >*e process by w*ic* a substance is c*anged from solid state toliuid state is called fusion. Fusion ta'es place at a fi?ed temperature calledmelting point 4M./.)

ree*e process by w*ic* a substance is c*anged from liuidstate to solid state is called freezing. Freezing ta'es at a fi?ed temperaturecalled freezing point 4F./.) For a substance M./ # F./.

M./. of a substance c*anges wit* t*e c*ange in pressure. Melting point of substances w*ic* contracts in t*e process of fusion 4as ice) decreases wit*t*e increase in pressure. Melting point of substances w*ic* e?pands in t*eprocess of fusion 4as wa?) increases wit* t*e increase in pressure.

&it* t*e addition of impurity 4as salt in ice), melting point of substancedecreases.

@vaporation causes cooling. >*is is w*y water in a eart* pot cooled insummer.

Noiling point of a liuid increases wit* t*e increase in pressure.= Noiling point of a liuid increases wit* t*e addition of impurity.

>*e amount of *eat reuired to c*ange t*e state of unit mass of substanceat constant temperature is called latent heat .

5 # mL.6.I. unit of latent *eat is oule 8 'ilogram

'u!limation T 6ublimation is t*e process of conversion of a solid directlyinto vapour.= 6ublimation ta'es place w*en boiling point is less t*an melting point.= 6ublimation is s*own by camp*or or ice in vacuum.

>oar rost T ;oar frost is ust t*e reverse process of sublimation i.e. it t*eprocess of direct conversion of vapour into solid.


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= 6team produces more severe burn t*an water at same temperaturebecause internal energy of steam is more t*an t*at of water at sametemperature

elative *umidity is measured by ;ygrometer.=elative *umiditymincreases wit* t*e increase of temperature..ir conditioning T For *ealt*y and favourable atmosp*ere of *uman3being, t*e conditions are as follows(i0 Temperature T From 10PC to 1%PC.(ii0 elative humidity T From -$ to -%.4iii) 'peed o) air T from $.% meter8minute to 1.% meter8minute. lf carbon dio?ide is suddenly e?panded, it is c*anged into dry ice. >*is isan e?ample of adiabatic process

6ound waves are longitudinal mec*anical waves.

Transverse /ave: If t*e particle of t*e medium vibrates perpendicular tot*e direction of propagation of wave, t*e wave is called transverse wave. &aves on strings under tension, waves on t*e surface of water aree?amples of transverse wave

*on3Mechanical wave or Electromagnetic wave: >*e waves w*ic* donot reuire medium for propagation i.e. w*ic* can propagate even t*roug*t*e vacuum are called non mec*anical wave.Lig*t, *eat are t*e e?amples of non3mec*anical wave. In fact all t*eelectromagnetic waves are non3mec*anical.D All t*e electromagnetic wave consists of p*oton.D >*e wavelengt* range of electromagnetic wave is "$ 3" to "$.

Properties o) electromagnetic wave:4i)

>*ey are neutral.


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4ii)

>*ey propagate as transverse wave.4iii)

>*ey propagate wit* t*e velocity of lig*t.4iv)

>*ey contain energy and momentum.4v)

>*eir concept was introduced by Ma?well.Following waves are not electromagnetic.

4i)

Cat*ode rays4ii)

Canal rays4iii)

Q rays4iv)

R rays4v)

6ound wave4vi)

Oltrasound wave

'ome 9mportant Electromagnetic /aveElectromagnetic/aves

?iscoverer

/avelength (in meter0

requencyrange

S3ays ;eneryNecueral

"$3" to "$3"$ "$1$ to "$"7

Z3 ays &.ontgen

"$3"$to "$37 "$"7 to "$"-

Oltra3[oilet rays itter "$37 to "$3 "$"- to "$"

[isible radiation !ewton 0.+ ? "$3to .7 ?

"$3

"$" to "$"1

Infra3red rays ;ers*el .7 ? "$3 to .7 ?"$30

"$"1 to "$"$

6*ort radio waves or ;ertz ;ertzianwaves

;einric* "$30 to " "$"$ to "$7

Long adio &aves Marcony " to "$ "$7 to "$-

Electromagnetic waves o wavelengt! range 10"# m to 10"2 m are calle$

microwaves.

/avelengthT &avelengt* is t*e distance between any two nearest particleof t*e medium, vibrating in t*e same p*ase


14/16

In transverse wave distance between two consecutive crests or troug*sand in longitudinal wave, distance between two consecutive compressionsor rarefaction is eual to wavelengt*

[elocity of wave # freuency ? wavelengt* or, v # n\.7haracteristic o) 'imple >armonic Motion&*en a particle e?ecuting 6;M passes t*roug* t*e mean positionT

4i)

!o force acts on t*e particle.4ii)

Acceleration of t*e particle is zero.4iii)

[elocity is ma?imum.4iv)

# 1]l8g

@lastic constant is of t*ree typesT4i)

BoungVs modulus of elasticity % # Longitudinal stress8 Longitudinalstrain

4ii)

Nul' modulus of elasticity K # [olume stress8 [olume strain4iii)

igidity modulus 4^) >angential 4or s*ear) stress8 s*ear strain

[iscosity is t*e property of liuid and gas bot*._ >*e viscosity of liuid is due to co*esive force between its molecules._ >*e viscosity of gas is due to diffusion of molecules from one layer toot*er layer.


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_ [iscosity of gases is muc* less t*an t*at of liuid. >*ere is no viscosity insolids._ [iscosity of an ideal liuid is zero._ &it* rise in temperature, viscosity of liuid decreases and t*at for gasesincreases._ [iscosity of fluid is measured by its coefficient of viscosity. Its 6I unit isdecapoise 4 'g8ms) or /ascal second. It is generally denoted by #+

Terminal 4elocity: &*en a body falls in a viscous medium, its velocity firstincreases and finally becomes constant. >*is constant velocity is called>erminal velocity.

In t*is situation, weig*t of body is eual to sum of viscous force and forceof buoyancy i.e. t*e net force on t*e body is zero. >erminal velocity of a sp*erical body falling in a viscous medium isproportional to t*e suire of radius of body.

>*e property of t*e sur)ace of a liuid t*at allows it to resist an e?ternal

force, due to t*e co*esive nature of its molecules. >*e co*esive forcesbetween liuid molecules are responsible for t*e p*enomenon 'nownas sur)ace tension

6urface tension of liuid decreases wit* t*e increase of temperature andbecomes zero at critical temperature

6mall insects suc* as t*e water strider can wal' on water because t*eir

weig*t is not enoug* to penetrate t*e sur)ace. Floating a needleT Acarefully placed small needle can be made to float on t*e sur)ace of water even t*oug* it is several times as dense as water

") ew dropsT ;ave you noticed t*e drops of water on t*e leaves in your garden in t*e early morning


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2 water dropletes , rain droplets are examples of suface tension.0) elative density # density of material 8 density of water at o C) 6ince, relative density is a ratio so it is unit less.%)-) Delative density is measured by ;ydrometer.) D>*e density of sea water is more t*an t*at of normal water. >*is

e?plains w*y it is easier to swim in sea water.7) D &*en ice floats in water its "8"$ t*e part remains outside t*e

water.+) DIf ice floating in water in a vessel melts` t*e level of water in water

does not c*ange."$) D/urity of mil' is measured by lactometer.

mercury column of - cm lengt* at $o

C at %o

latitude at sea3level " bar # "$% !8m1

Atmosp*eric pressure " atm # ".$"?"$% !8m1 # -$ torr D Atmosp*eric pressure decreases wit* altitude 4;eig*t from eart*surface). >*is is w*y 4i) it is difficult to coo' on mountains 4ii) >*e fountainpen of a passenger lea's in aeroplane at *eig*t.D Atmosp*eric pressure is measured by barometer. &it* t*e *elp of barometer, weat*er forecast can be made.D 6udden fall in barometer reading is indication of storm.

D 6low fall in barometer reading is indication of rain. 6low rise in barometer reading is t*e indication of clear weat*er.

;ydraulic lift, ;ydraulic press, ;ydraulic brea' wor's on /ascal law.

>*e melting point of a substance w*ic* e?pands on fusion increases wit* t*eincreases in pressure, for e?ample Y &a?.

4ii)

>*e melting point of a substance w*ic* contracts on fusion decreaseswit* t*e increases in temperature, for e?ample 3 ice.

4iii)

Noiling point of all substances increases wit* t*e increases inpressure.

luminous intensity

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