Physics Paper-2 CSE Questions

8/10/2019 Physics Paper-2 CSE Questions

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(ii! An electron havin& an ener&y " ev is travelin& in the re&ion where ('! varies asshown below>

alculate the 7e ro&lie wave len&th of the electron in re&ion ? ?? and ???.("003!

13. (i! ?f ' and @'are two conu&ate variables show that(: '! (: @'! BC'@'DE/"i

(ii! An electron has a speed of - 10*m/s accurate to 0.01%. +ith what fundamental

accuracy can we locate the position of electron, ("00-!1-. alculate the wave len&th of neutrons at a temperature of "0G .

("00-!1*. alculate the de ro&lie wavelen&th of an electron movin& with a 5inetic ener&y of 1;e.

12. alculate the de ro&lie wavelen&th of a thermal neutron at 0"6 Ctemperature.

("002!16. (i! #tate and e'plain 4eisenber&s uncertainty principle. ='perimental data reveal that no electron in

an atom has ener&y &reater than - ;e. Assumin& that the radius of a nucleus is 1-10 m show usin&

4eisenber&s uncertainty principle that an electron cannot e'ist inside the nucleus.(ii! alculate the de ro&lie wavelen&th of thermal neutrons at 300 ). ("006!

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(Sc"#o$in%e#&s 'ae e*a!ion an$ a+ica!ions)

(1! +rite down #chrodin&ers eHuation in one dimension and e'plain the si&nificance of the ei&en values andei&en functions of this eHuation.#olve the #chrodin&ers eHuation if the potential function is &iven as

('! I o(a constant! for"

a'< .

I 0"

a'for >

#tate the boundary conditions you use alon& with their ustification. (?n the solution consider particlesincident from one side only!. ?f the total ener&y = B o show that there is an important difference withclassical mechanics. ='plain with the help of the uncertainty principle that = B odoes not mean that5inetic ener&y is ne&ative. (18!

("! #et up #chrodin&ers eHuation for a one$dimensional harmonic Jscillator. Assumin& that the solution is

of the form !'(feA"'= where is a polynomial in ' find the ener&y ei&en values and the &round

state ei&en function. omment on the relation between the &round state ener&y and 4eisenber&s

uncertainty principle. (10!(3! #et up #chrodin&ers eHuation for a free particle confined in a cubical bo' and find the ener&y ei&envalues. +hat form will @auli principle ta5e for elections in such a bo', 7educe the Kero point ener&y ifthe len&th of the bo' be 10 $10metre and there be 10 electrons in it. (

('! I 0 ' B 0 ('! I 0 ' E 0

(a! #uppose the election has the ener&y = E 0and is incident from $' direction find the normaliKed wavefunction so it corresponds to unit incident flu'.

(b! #olve the above problem for the case = B 0and discuss the si&nificance of the result with the help of asuitable e'ample.

(12!

(8! +rite down the time independent #chrodin&er eHuation for the ' B 0 and ' E 0 in case of a step potential ('! I 0 ' B 0

I 0 ' 07iscuss the solutions thus obtained for the case = E o. Jbtain the followin& relations

""

0

""

1

"

R- O p )0O YG

)O R O R O R- ("002!

"6. ?n the followin& reactions indicate with an e'planation whether they proceed by stron& electroma&neticor wea5 interaction or they are forbidden >

RO OO_p n O eOO_e

p O R- $O )O ("002!

"8. #tate the Huantum numbersIZ j and# for the uds Huar5s and antiHuar5s. +hich combination of theseleads to the formation of (1! proton and ("! neutron, ("006!

". ive some characteristic properties of stran&e particles which distin&uish them from non Q stran&e ones.

+rite the ell;ann$Vishiima relation. 4ow is it used for the classification of elementary particles, ("006!

30. ='plain why the decay process n p O e O_ is observed but the decay p n O eOO_isnot observed.. ("008!

31. ='plain lepton number conservation and why it is necessary to distin&uish between different types ofneutrinos, ("008!

3". ive the hyperchar&e and isospin of the Huar5s and antiHuar5s. +hat are the Huar5 contents of the

mesons> G -)O )G )

- and k ("008!


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SUPERCON.UCTIVITY

1. +hat is #uper conductivity, ?n what 5inds of materials is it found to occur, Vame some parameterswhich characterise a super conductor. ite any two maor uses if we succeed in ma5in& #uper conductorswith


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(Ban$ !"eo#/ o0 so+i$s)

1. #tate the difference in the electronic ener&y states in an isolated atom and in a solid. 4ence e'plaindifference between a conductor an insulator and an intrinsic semiconductor. +hat is the role ofimpurities in so called e'trinsic semi conductors,

(18!

". +hy do the electronic ener&y levels in a solid form bands, 7escribe in terms of the band theory thedifference between a conductor an intrinsic semi conductor and an insulator.4ow do the ener&y levels chan&e when some impurities are introduced in a #emi$conductor, ='plainhow by dopin& you can have both n$type and p$type semi conductors startin& with pure ermanium.


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(SEMI CON.UCTORS)

1. +hat is a @$V unction, 7escribe with ener&y level dia&ram the formation of double layer of char&eswhich &enerates a potential difference (! across the unction. 4ence show that the capacitance of thedouble layer I)$1/" where ) is a constant. #tate some practical use of this relation between ].

(188!

". +hat is a Zener diode, ='plain what function it performs in the circuit &iven below as the loadresistance LNis varied. +hat is the purpose of introducin& resistor L" in the circuit, (s and Lsrepresents source volta&e and resistance respectively!.

(18!3. 4ow is a p$n unction prepared, ='plain the char&e and potential distributions in such a unction in

open circuit. ='plain how a p$n unction can be used to build a solar cell. 7escribe the mechanism ofthe increase of conductivity of ermanium by dopin& it with Arsenic.

(10!-. ='plain the formation of potential barrier in an unbiased p$n unction.

(1"!*. #how that in the non$de&enerate appro'imation the Fermi level in a n$type semiconductor is sli&htly

below the bottom of the conduction band and in p$type it is sli&htly above the top of the valenceband but in both cases it remains within the band &ap.(13!

2. 7escribe and e'plain the theory and operation of the Kener diode. ='plain what is meant bya. Avalanche brea5 downb. Zener brea5 down

(13!6. 4ow does built in potential appear across a p$n unction, ='plain under what biasin& conditions drift

and diffusions currents respectively dominate.(1*!

8. +hat is the photovoltaic mode of operation of a photodiode, 7escribe the construction and wor5in&of a silicon solar cell.

(18!. 7iscuss the different brea5down mechanisms for a reverse biased Zener diode.

("000!10. 7o these mechanisms have different temperature coefficients, ='plain.

+hich one of these mechanisms shows a ne&ative dynamic resistance, +hy,("000!

11. A Zener diode of 1 + power has a dynamic resistance of 10 mat the brea5down volta&e of 3 .+hat will be the fluctuations in the current throu&h the diode if the volta&e fluctuates by 100 m,+hat will happen to the diode, +hy,

("000!1". (a! 7erive the various current components in a pQnQp transistor when it is actively biased. sin&

=bers Q;oll model show that for the common Qemitter confi&uration

?I Q ?=I Q ?J/

1V V

C Te

+here the symbols have the usual meanin&. ("003!(b! ?n the followin& circuit


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#how that the stability factor # is &iven by

# I

1

1 e

e b

R

R R

+

++

+here LbI1 2

1 2

R R

R R+("003!

13. A transistor with I *0 =I 0.6 I "".* and LI *.2 5 is used in biasin& circuit asshown in the fi&ure. ?t is desi&ned to establish the Huiescent potential at =I 1" ?I 1.* mA andstability factor # 3. Find the values of resistors L= L1 and L"where symbols have their usualmeanin&s.

("00-!1-.


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TUTORIAL SHEET: 11(TRANSISTORS)

1. 7iscuss briefly the various ways of modulation of electroma&netic waves for the purpose ofcommunications throu&h radio and television.

(188!". +rite short note on


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(10!". 7raw a circuit usin& AV7 JL and VJ< &ates to realiKe the followin& truth table> ?nput JutputA 70 0 0 00 0 1 10 1 0 1

1 0 0 10 1 1 01 0 1 01 1 0 01 1 1 13. 7efine e'$JL. ive its truth table and draw the possible lo&ic bloc5s.

(12!-. #implify the followin& lo&ic function and draw the correspondin& lo&ic &ates>

AAAAAj ++++++=(16!

*. #implify the followin& lo&ic function and draw the correspondin& lo&ic dia&ram>$

j I (AO!. (AO!. (O! (18!2. #implify the &iven ooleam e'pression and draw the correspondin& lo&ic circuit usin& VAV7 &ates

jI(A !.(A !+ + + +(1!

6. (a! ombination switchin& circuit can perform an addition of the numbers held in two re&isters.(i! +rite down the truth table for the addition of two bits.(ii! +rite down a oolean e'pression for ht necessary circuit functions.(iii! Arrive at the ='clusive QJL function.(iv! 7raw the lo&ic dia&ram for the circuit which performs the addition.

(b! (i! +hat is seHuential switchin& circuits,

(ii! 7escribe a simple seHuential circuit.(iii! 7escribe a cloc5ed L# Flip QFlop.(iv! riefly describe LJ;s.

("001!8. #how that a ne&ative lo&ic JL &ate is li5e a positive lo&ic AV7 &ate.

("00"!. ='plain the operation of the followin& circuit as a &ate. 7raw the truth and find the operation carried

out by this &ate ne&lectin& the source impedance

[unction saturation volta&es and diode volta&es in forward direction. Find the minimum value of h fe.("003!

10. (a! ive the two forms of the 7e ;or&ans theorem.(b! +hat is the principle used in half Qadder, ive the truth table for it.

("00-!


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TUTORIAL SHEET: 15E+ec!#onics: Misce++aneo*s

(1! (a! F=< have a uniHue properties ma5e [

iven that &mI 10 m/A rdI 1 ; and ZNI 10 5.

("003!

(-!

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Physics Paper-2 CSE Questions