12 Physics Usp Sp by Aneesh

7/27/2019 12 Physics Usp Sp by Aneesh

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Code No. 52/1/2

Roll No.:

PHYSICS (Theory)

Time allowed: 3 hour !a"imum !ar#: $%

&e'eral I'ruio':

1. All questions are compulsory.2.

There are 30 questions in total. Questions 1 to 8 carry one mark each,questions 9 to 18 carry two marks each, questions 19 to 27 carry three

marks each an questions 28 to 30 carry !i"e marks each.

3. #se o! calculators is not permitte.$. %ou may use the !ollowin& "alues o! physical constants where"er necessary'

c ( 3 ) 108ms*1

h ( +.+2+ ) 10*3$s

e ( 1.+02 ) 10*19- 0( $ / ) 10*7T m A*1

ass o! neutron mn 1.+7 ) 10*27k&

olt4mann5s constant k ( 1.381 ) 10*23 6*1

A"o&aro5s numer A( +.022 ) 1023 mol *1

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1. What is the effect of slit width and wave length of light source on fringe width of the fringesformed by youngs double slit experiment?

2. What is ionisation potential? Calculate it for hydrogen atom?. Calculate the threshold fre!uency of photon for photoelectric emission from a metal of wor"

function of #.1 e$?

%. &wo beams one of red light and another of blue light' of the same intensity are incident on themetallic surface to emit photo electrons. Which one of the two beam emits electrons of

greater "inetic energy?

Please check that this question paper contains 3 printed pages. Code number given on the right hand side of the question paper should be

written on the title page of the answer-book by the candidate. Please check that this question paper contains 30 questions. Please write down the serial number of the question before attempting it.


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,. -xpress the angular magnification of an compound microscope in terms of the focal length ofobective and eye piece.

/. What is the critical angle for a material of refractive index0. Write the function of base region of a transistor. Why this region is made thin and slightly

doped?

. &he image of a candle formed by a convex lens is obtained on a screen. Will the full sie imageof the screen is obtained' if the lower half of the lens is painted blac" and completely opa!ue?

3llustrate your answer with a ray diagram.

1#. 4raw a plot of potential energy of a pair of nucleons as a function of their separation. Writetwo important conclusions' which you can draw from the graph regarding the nature of

nuclear forces.

11.5ame any two types of transmission media that are commonly used for transmission ofsignals? Write the range of fre!uencies of the signals for which these transmission media are

used.

12. 6 proton and a 7* particle are accelerated from rest by the same potential. 8ind the ratio oftheir de*9roglie wave length.

1. 8or the same angle of incidence' the angle of refraction in three media 6' 9 and C are 1(#' 2(#and (

#respectively. 3n which medium the velocity of light will be minimum?

1%. :how that in case of a prism 6 ; < = i ; e' where the symbols have their usual meanings.1(. Why is fre!uency modulation preferred over amplitude modulation for transmission of music?1,. With the help of one example' explain how the neutron to proton ratio changes during alpha

decay of a nucleus.

1/. 4raw a labelled diagram of an astronomical telescope forming the final image at infinity. Writedown the formula for its magnifying power.

10. &wo light waves of amplitude a1 and a2 interfere with each other. 8ind the ratio of theintensities of maxima to minima.

1. 6 carrier wave of pea" voltage 12 $ is used to transmit a message signal. What should be thepea" voltage of the modulating signal in order to have a modulation index of /(?

2#. 4efine threshold fre!uency. 3f the fre!uency of the incident radiation is greater thanthreshold fre!uency >#@ how will the stopping potential vary' if fre!uency >@ is increased'

"eeping other factors constant.

21. &he value of ground state energy of hydrogen atom is A1., e$.


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>b@ Bow much energy is re!uired to ta"e an electron in this atom from the ground state tosecond excited state?

22.What is meant by stopping potential? +lot a graph showing the variation of photo electriccurrect with anode potential for

>i@ two light beams of same fre!uency but different intensity>ii@ the light beams of different fre!uencies but same intensity. What inference can you

drawn from each graph

2. What is the phenomenon of polarisation of light? 4erive the relation connecting the polarisingangle of the medium and its refractive index.

2%. 3n a single slit diffraction pattern' how does the width of the central bright maximum changewhen

>a@ the slit width is decreased>b@ the distance between the slit and the screen is increased and>c@ light of smaller wave length is used.Dustify your answer.

2(. &he input resistance of a silicon transistor is ,,(E. 3ts base current is changed by 1(F6' whichresults in the change in collector current by 2 m6. &his transistor is used as a common emitter

amplifier with a load resistance of ( "E. Calculate >i@ current gain ) a.c.>ii@ transconductance gm

and >iii@ voltage gain 6vof the amplifier.

2,.&wo radioactive nuclei G and H initially contain an e!ual number of atoms. &heir half life is 1hour and 2 hours respectively. Calculate the ratio of their rates of disintegration after two

hours.

2/. 3n figure below' circuit symbol of a logic gate and two input waveforms 6 and 9 are shown.5ame the logic gate' write its truth table and give the output wave form.

20. 4raw a circuit diagram to study the input and the output characteristics of a n*p*n transistor inC-*configuration. :how this characteristic graphically. -xplain how current amplification factor

of the transistor is calculated using output characteristics?


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the refraction of plane wave front incident at a plane surface. Bence verify :nells law of

refraction. 3llustrate with the help of diagrams' the action of >i@ Convex lens >ii@ Concave

mirror when a plane wave front incident on it.

#. >a@-xplain briefly with the help of diagrams the terms >i@ amplitude modulation >ii@ fre!uencymodulation. Which one of these gives better !uality transmission and larger coverage?

>b@ What is meant by modulation and demodulation? -xplain the process of demodulation

with the necessary bloc" diagrams.

ANEESH VV

Academic Coordinator & Senior Physics Teacher

TDIS, Indonesia

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12 Physics Usp Sp by Aneesh