Physics Papers

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Year 2000

FEDERAL PUBLIC SERVICE COMMISSION COMPETITIVE EXAMINATION FOR RECRUITMENT TO POSTS

IN BPS 17 UNDER THE FEDERAL GOVERNMENT, 2000

PHYSICS PAPER - I TIME ALLOWED: 3 HOURS MAXIMUM MARKS: 100

Note:- Attempt FIVE questions in all, including Question No.8 which is compulsory.All questions carry equal marks.

1. (a) Find a unit vector which is perpendicular to the vectors +j and j + ?. (5)(b) If A = xz y2 j + 2x2y? and =x2yz2, find (15)

2. (a) Define angular momentum of a single particle and derive a relation between torqueand angular momentum. (10)(b) Calculate the angular momentum, about the Earths center of a 50 kg person on theequator of the rotating earth. (10)

3. Describe with the help of necessary diagrams the details of Michelson-Morley experiment.What was the conclusion drawn from the results of the experiment. (20)

4. (a) Write down Maxwells distribution function for molecular speeds in a gas. Give thedetails of various parameters involved. (10)(b) A container filled with N molecules of Oxygen gas is maintained at 300 K. What fractionof the molecules has speeds in the range 599-601 m/see? The molar mass M of Oxygen is0.032 kg/mole. (10)

5. Differentiate between Phase and Group velocities. Given that phase velocity V of waves in

deep water is (g l /2p ) 1/2 ,find their group velocity v. (20)6. What is interferometer? Describe the construction and working principle of aninterferorneter with which you are familiar. (20)

7. Write short notes on the following;(a) Viscosity(b) Planetary Motion(c) Laws of Thermodynamics and their importance in daily life. (20)

COMPULSORY QUESTION

8. Write only the correct answers in the answer book. Do not reproduce the

questions.

1) If the speed of particle is doubled then its kinetic energy becomes(a) Doubled.(b) Unchanged(c) Four time.(d) Half of the initial value

2) A ping - pong ball of mass m moving with velocity v bounces off a concrete surface with


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the same speed in the opp osite direction. The change in its linear momentum is (a) 2mw(b) mv(c) 1/2mv(d) Zero

3) The work done by a force of 20 N in displacing an object through a distance of 5 cm is(a) 100 J(b) 4 J(c) 400 J(d) 1 J

4) The weight of an astronaut in space far from any planet in(a) Zero(b) Different than on earth(c) Same on earth

5) A net force needed to give a mass of 250 kg an acceleration of 5 cm/sec2 is(a) 25N(b) 12.5N(c) 10N(d) 5N

6) A light year is a unit of(a) Time(b) Distance(c) Velocity(d) Intensity of light

7) A spaceship is circling a planet at a distance of 10000 km from its center. Assume thatthe radius of the planet is 5000 km mid the acceleration clue to gravity on its surface is 10

rn/sec2. The speed of the spaceship is(a) 5 km/sec(b) 1 km/sec(c) 10km/sec(d) 25 km/sec

8) A uniform spring with force constant K is cut into halves. Whet is the spring constant forone of the halves?(a) Half of the original one.(b) Twice the original one(c) 1/4 of original one(d) Same original one

9) A watt is the unit of(a) Energy(b) Power(c) Work(d) Capacity

10) Two bodies are in thermal equilibrium with each other if they have same(a) Pressure(b) Density


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(c) Energy(d) Temperature

11) The number of grams in one mole of Helium gas are(a) 1gm/mole(b) 4gm/mole

(c) 6 gm/mole(d) 2 gm/mole

12) A gas consists of a mixture of He and N2 molecules The speed of He molecules Intl.mixture is(a) Slower than N2 molecules(b) Greeter than N2 molecules(c) equal to N2 molecule.

13) If a gas is compressed constant temperature, then the mean free path of the moleculesof the gas,(a) decreases(b) remain the same(c) increases

14) The melting point of the element Sulfur is 113 C. Its temperature at Fahrenheit s caleis(a) 45 F(b) 113 F(c) 63 F(d) 8l F

15) Diffraction of waves occurs because of(a) medium change(b) uncertainty principle

(c) geometry of the object obstructing the wave(d) none of these

16) Beats in sound are a result of(a) two sound waves with different speeds(b) in-homogenous medium(c) superposition of two waves with different frequencies(d) the relative motion of one of the sound source.

17) Light of certain colour is composed of train of waves, each 0.250 m long. The number ofwaves in 1 meter distance are(a) 2500000(b) 5000000(c) 4000000(d) 250

18) Longitudinal waves do not exhibit(a) refraction(b) reflection(c) diffraction(d) polarization


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19) If mass of a simple pendulum is doubled, its period (a) remain unchanged(b) doubled(c) becomes half of the original(d) None of these

20) Diagnostic ultrasound of frequency 4.50 MHz is used to examine tumors in soft tissue. Ifthe speed of sound in tissue is 1500 m/sec. The wave length of this wave in tissue is(a) 6750 mm(b) 4.50 mm(c) 1500 mm(d) 333.3 mm


IN BPS 17 UNDER THE FEDERAL GOVERNMENT, 2005.

PHYSICS PAPER- II TIME ALLOWED: THREE HOURS MAXIMUM MARKS:100

NOTE: Attempt FIVE questions in all, including question No.8 which isCOMPULSORY. All questions carry equal marks.

Q.1. (a) A dielectric sphere is placed in a uniform electric field. Draw a neat diagramshowing a distortion produced in the field. Calculate, electric field outside and inside thedielectric sphere. (10)(b) Explain the dielectric polarization. Establish a relation between electric field strength E,polarization P and electric induction D. (10)

Q.2 (a) Give a brief account of the phenomenon of electromagnetic induction. Describe twoexperiments to demonstrate it. (10)(b) Prove a relation between the induced e.m.f. and. the rate of change of lines of magneticforce through a circuit (10)

Q.3. (a) What is transistor biasing? How will you connect a PNP transistor in i) common baseand ii) common emitter configurations. Draw their characteristics curves and discuss theircurrent gain, voltage gain and input impedance. Give the applications of two configurations.(12)(b) Deduce the conditions under which the discharge of a condenser is Oscillatory incharacter. Find an expression for the frequency of oscillations. (8)

Q.4. (a) Outline the basic facts of Photo electricity. Give the law of Photoelectric emission.How can they be explained? (12)(b) The kinetic Energies of photoelectrons range from zero to 4.0x1019J, when light ofwavelength 3000 A falls on a surface, what is the stopping potential for this light? What isthe threshold wavelength for the material? (8) (1 eV= 1.602x1O19J.)

Q.5. (a) State f undamental postulates of Bohrs Theory of hydrogen atom Derive themathematical expression for energy of electron in hydrogen atom. Give the interpretation ofnegative sign. (12)(b) Give an account of different series of Spectral lines of hydrogen atom. (8)


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Q.6. (a) Give the significance of Schrodingers Wave equation in wave mechanics. Apply itto calculate energies of particle in a box and discuss the results. (12)(b) What is Ileisenbergs Uncertainty principle? Explain its importance in the developmen t ofphysics. (8)

Q.7. Write a short essay on any two of the following: (20)(a) Nuclear Reactors and their classifications(b) Mass Spectrometer and Isotope detection(c) AM Radio Receivers and Transmitters

COMPULSORY QUESTION

Q. 8. Write only the corre ct answer in the answer book. Dont reproduce thequestions: (20)

(1) The neutrino does not possess(a) charge(b) linear momentum(c) angular momentum(d) energy

(2) The particle whose properties are most nearly the same as those of the proton is the(a) positron(b) neutron(c) antiproton(d) positive ion(e) none of these

(3) The element whose nuclei contain the most tightly bound nucleons is

(a) helium(b) carbon(c) iron(d) uranium(e) none of these

(4) As a sample of a radioactive nuclide decays, its half life(a) decreases(b) remains the same(c) increases(d) any of the above, depending on the nuclide

(5) Current in an n-type semiconductor is carried by(a) electrons(b) holes(c) positive ions(d) electrolytes(e) none of these

(6) Paulis exclusion principle states that no two electrons in an atom can(a) be present in the same probability cloud(b) have the same spin


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(c) have, the same quantum numbers(d) interact with each other(e) none of these

(7) The number of possible orientations of an atomic electron in a magnetic field is(a) 1

(b) 2(c) 4(d) 2p(e) none of these

(8) A hydrogen atom is in its ground state when its orbital electron(a) is within the nucleus(b) has escaped from the atom(c) is in its lowest energy level(d) is stationary(e) none of these

(9) Electromagnetic waves transport(a) wavelength(b) frequency(c) charge(d) energy(e) all of these

(10) The reactance of a capacitor is proportional to(a) f(b) f(c) f2(d) 1/f(e) none of these

(11) The capacitive reactance of a 5-m F capacitor in a 20-kHz circuit is(a) 0.63W(b) 1.6W(c) 5W(d) 16W(e) none of these

(12) The impedance of a circuit does not depend on(a) I(b) f(c) R(d) C(e) all of these

(13) At resonance, itis not true that(a) R=Z(b) XL=1/XC(c) P=IV(d) I=V/R

(14) A voltmeter across an AC circuit reads 50 V and an ammeter in series with the circuit


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reads 5 A. The power consumption of the circuit(a) is less than or equal to 250 W(b) is exactly equal to 250 W(c) is equal to or more than 250 W(d) may be less than, equal to, or more than 250 W(e) none of these

(15) The magnetic flux through a wire loop in a magnetic field B does not depend on(a) the area of the loop(b) the shape of the loop(c) the angle between the plane of the loop and the direction of B(d) the magnitude B of the field(e) none of these

(16 The alternating current in the secondary coil of a transformer is induced by(a) a varying electric field(b) a varying magnetic field(c) the iron core of the transformer(d) motion of the primary coil(e) none of these

(17) When a diamagnetic substance is inserted in a current carrying solenoid, the magneticfield is(a) slightly decreased(b) greatly decreased(c) slightly increased(d) greatly increased(e) none of these

(18) The N-type semiconductor is electrically(a) negative

(b) positive(c) neutral(d) charged

(19) When a 100 W, 240-V light bulb is operated at 200 V, the current that flows in it is(a) 0.35 A(b) 0.42 A(c) 0.50 A(d) 0.58 A(e) none of these

(20) The a of a transistor is(a) current gain in common base(b) current gain in common emitter(c) voltage gain in common emitter(d) voltage gain in common base(e) none of these

__________________

Year 2001


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IN B.P.S. 17, UNDER THE FEDERAL GOVERNMENT, 2001

Time Allowed: 3 hoursMaximum Marks: 100

PAPER I

Note: Attempt FIVE questions in all, including Question No. 8, which is compulsory. Allquestions carry equal marks.

Q1. Three vectors are given by:a = 3i + 3j -2kb = -i - 4j + 2kc = 2i + 2j kFind (i) a. (b. c), (ii) a. (b. + c), (iii) a. (b + c)

Q2. (a) State the basic postulates of special theory of Relativity. Discuss the effect ofrelative uniform motion on Mass, Length and Time.(b) A rod lies parallel to the x-axis of reference frame S, moving along this axis at a speedof 0.632 C. Its rest length is 1.68m. What will be its measured length in frame S?

Q3. (a) What is meant by Interference of Light? Also distinguish between ConstructiveInterference and Destructive Interference.(b) Derive an expression for the Resolving Power of a plane diffraction grating.(c) Monochromatic light emitted from He- Ne laser source with = 632.8 nm is inciden tnormally on a diffraction grating containing 6000 lines per cm. Find the angles at which onewould observe the first order maximum and the second order maximum. Will it be possibleto observe the third order maximum as well?

Q4. (a) Differentiate between Travelling Waves and Standing Waves.(b) Prove that the Rate of Transfer of Energy in wave motion depends on the square of thewave amplitude and square of the wave frequency. (marks 10)(c) Spherical waves travel from a source of waves whose power output, assumed constant,is P. What will be the wave intensity I at a distance from the source?

Q5. Write an essay on the production and measurement of low temperatures.

Q6. State and explain the First Law of Thermodynamics. Discuss its applications in the caseofa. Adiabaticb. Isothermalc. Isochoricd. Isobaric Processes

Q7. Write notes on any TWO of the following:a. Bernoullis Theorem b. Laser and its Applicationsc. Brownian Motion

Q8. Write only the correct answer in the Answer Book. Dont reproduc e the


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questions.

1. The vector in space has:a. Three componentsb Two componentsc. One component

d. None of these

2. The correct relation is:a. a . b = b . ab a . b b . a c. a b = b ad. a . b = b a

3. N.s./m^2 is the SI unit of:a. Surface tensionb. Viscosityc. Forced. Momentume. None of these

4. Antinodes are points where:a. Strain is maximumb. Frequency is maximumc. Wave length is maximumd. Amplitude is maximume. None of these

5. When the mass and speed of a body are doubled, the momentum becomes:a. 16 times

b. 8 timesc. 4 timesd. 3 timese. None of these

6. Efficiency of carnot engine is 100% when temperature of sink is:a. Zerob. Infinitec. Equal to sourced. None of these

7. For gases obeying Boyles Law, if pressure is doubled, volume becomes:a. Doubleb. One halfc. Three timesd. No change

8. Distance between an antinodes and an adjacent node is:a. b. 2c. /2 d. /4


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9. Total energy of a particle performing S.H.M. is directly proportional to:a. The amplitudeb. The square root of amplitudec. The square of amplituded. The reciprocal of amplitude

e. None of these10. Frequencies less than 20 Hz are called:a. Supersonicsb. Ultrasonicsc. Infrasonicsd. None of these

11. Laser is an intense beam of light which isa. Monochromaticb. Coherentc. Collimatedd. All of the above

12. The change in entropy S of a system is given by: a. S = Q/T b. S = T Q c. S = T/Q d. None of these

13. The particle nature of light if evidenced from:a. Polarisationb. Interferencec. Diffractiond. Photoelectric Effect

e. None of these14. Sound waves area. Electromagnetic wavesb. Mechanical wavesc. Transverse wavesd. Radio wavese. None of these

15. Kilo Watt Hour (KWh) is a unit of:a. Electric Fluxb. Electric Fieldc. Electric Energyd. Electric Potentiale. None of these

16. All motions are:a. Absoluteb. Uniformc. Relatived. None of these


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17. The normal human body temperature on Fahrenheit scale is:a. 96Fb. 98.6Fc. 99Fd. 100F

18. We get light inside a room in daytime due to:a. Diffractionb. Interferencec. Polarisationd. Refractione. None of these

19. The radiation which gives sense of heat is called:a. Visible lightb. Invisible lightc. Infra-red radiationd. Ultra violet rayse. None of these

20. Heat death will occur when:a. Temperature is maximumb. Temperature is minimumc. Heat energy is zerod. All bodies are at the same temperaturee. None of these




PAPER II


Q1. (a) What is a point charge? Why do we take a point charge while estimating the electricfield intensity of a system of charge?(b) What do you understand from Coulombs law and Gausss law? Do they represent thesame fact (law)? If yes how; if no why?(c) a 24-volt lamp has a resistance of 8 ohms. What resistance must be placed in serieswith it, if it is to be used in a 117-volt line?

Q2. (a) What requirements must be met to form an electric circuit? Is there any similaritybetween an electric and a magnetic circuit? Explain the terms MMF and reluctance.(b) Discuss the statement: In case of a transformer whatever is gained is voltage is lost incurrent. (c) What causes the magnetism? Differentiate between Dia-, Para-, Ferromagneticmaterials.


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Q3. (a) In how many ways electrons can be emitted from various materials? Describethermionic emission in detail and establish the Childs law. (b) What is meant by modulation? Describe its various types and show that a 100%amplitude modulation increases the radiated power by 50%.(c) Calculate the frequency of radio waves coming out of an oscillating circuit containing a

capacitor of 0.02 microfarad and an inductor of 8 microhenry.Q4. (a) How would you calculate and of a triode from its characteristic curves?(b) What is rectification? How is it achieved? Draw fully labelled circuits for half-wave andfull-wave rectifiers.(c) Explain how P-, and N-type semiconductors are produced? Elaborate the concept of a

hole.

Q5. (a) Discuss various models put forward to explain the atomic structure/ describe theadvantages and disadvantages of each model and show how the shortcomings of one modelwere overcome by the subsequent model?(b) Explain the significance of Paulis principle. (c) An electron is moving with a velocity of m/s. Calculate the energy in electron-volts. Massof electron is given as g?

Q6. (a) Obtain expression for the wave numbers of lines belonging to different series ofhydrogen atom. Draw suitable diagrams to show hydrogen spectrum.(b) Find de-Broglie wave length of helium atoms (mass kg) having average velocity m/s.Plancks constant is Js.

Q7. (a) Explain that radioactive rays are of inter-nuclear origin.(b) What is chain reaction in nuclear fission? Explain controlled and uncontrolled chainreactions.

Q8.Write only the c orrect answer in the Answer Book. Dont reproduce the

questions. (1) A negative electric charge:(a)Interacts only with positive charges(b)Interacts only with negative charges(c)Interacts with both positive and negative charges(d)May interact with either positive or negative charges, depending on circumstances(e)None of these

(2) Ten thousand electrons are removed from a neutral pith ball. Its charge is now(a) +1.6 10 ^(-15)(b) +1.6 10 ^(-23)(c) -1.6 10 ^(-15) C(d) -1.6 10 ^(-23) C(e)None of these

(3) If air is replaced by an other medium, the force between two charges:(a)Increases(b)Decreases(c)Remains the same(d)May increase or decrease depending upon the nature of medium(e)None of these


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(4) The result of placing soft iron inside a coil is:(a)Increase in magnetic flux(b)Decrease in magnetic flux(c)No change in the magnetic flux(d)None of these

(5) The appearance of an electric field in a conductor when it is moved across a magneticfield is an example of:(a)Lenzs law (b)Ohms l aw(c)Electromagnetic induction(d)Magnetic flux(e)None of these

(6) The primary winding of a transformer has 200 turns and its secondary winding has 50turns, if the current in the secondary winding is 40 A, the current in the primary is:(a)10 A(b)80 A(c)160 A(d)8000 A(e)None of these

(7) The energy content of a charged capacitor resides in its:(a)Plates(b)Potential difference(c)Charge(d)Electric field(e)None of these

(8) In an ac-circuit, the voltage:

(a)Leads the current(b)Lags the current(c)Is the phase with the current(d)Any of the above, depending on the circumstances(e)None of these

(9) Amount of energy liberated in Fission reaction of one atom of is nearly:(a)200 MeV(b)20 MeV(c)20 eV(d)200 eV(e)None of these

(10) Substance which can be used as moderator in a reactor is:(a)Graphite(b)Heavy water(c)Cadmium(d)Uranium(e)None of these

(11) The half-life of phosphorus 32 is 15 days. A given mass of phosphorous 32 will reduceto of its original mass in:


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(a)60 days(b)30 days(c)45 days(d)90 days(e)None of these

(12) Which of the following fundamental particles is heaviest:(a)Electron(b)Muon(c)Neutrino(d)Meson(e)None of these

(13) Fission reaction U^235 of is:(a)Exothermic(b)Endothermic(c)None of these

(14) For an atom having atomic number, Z, and atomic weight, A, the number of neutronsin a nucleus is:(a)A(b)Z(c)A+Z(d)A-Z

(15) Normally the emitter of the transistor has to be:(a)Forward biased(b)Reverse biased(c)May be forward biased or reverse biased(d)May not be biased(e)None of these

(16) The inductance in a coil plays the same role as:(a)Inertia plays in mechanics(b)Energy plays in mechanics(c)Momentum plays in mechanics(d)None of these

(17) If the current flowing through a lamp drops by 1 per cent, what will be the percentagedecrease 1 power?(a)0.01%(b)1%(c)2%(d)4%(e)None of these

(18) Modern physical theories indicate that:(a)All particles exhibit wave behaviour(b)Only moving particles exhibit wave behaviour(c)Only charged particles exhibit wave behaviour(d)Only uncharged particles exhibit wave behaviour(e)None of these


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(19) A neon sign does not produce:(a)A line spectrum(b)An emission spectrum(c)An absorption spectrum(d)Photons(e)None of these

(20) The splitting of the spectral limes of an element when it radiates in a magnetic field isknown as:(a)The Schrodinger effect(b)The Zeeman effect(c)Induced emission(d)Population inversion

__________________P.R.

Year 2002




PAPER I


Q.1 (a) If A = A_1^i + A_2 i + A_3 j and B = B_1 i + B_2 j + B_3 k, then prove that A,B =A_(1 ) B_1 + A_2 B_2 + A_3 A_3(b) Find the value of e so that A = ci 2j + k and B = 2ci + cj 4k are perpendicular.(c) If A, B C = 0, then show that vectors A, B, and C are coplanar. Given = 3x^(2 ) -yx, find div. (grad )

Q.2 (a) Show that Newtons first law of motion is a special case of Newtons second law ofmotion.(b) State and explain the law of conservation of linear momentum.(c) A stream of bullet whose mass m = 3.8g each, is fired horizontally with speed v =1100m/s into a large wooden block of mass M = 12kg that is initially at rest on horizontaltable. If block is free to slide without friction across the table, what speed will it acquireafter it has absorbed 8 bullets?

Q.3 (a) Drive Bemoullis equation for steady flow of a non -viscous fluid.(b) a liquid is discharging from an orifice in a large tank at a distance h below the liquidsurface. The tank is open at the top. Show that the speed of efflux is v = 2gh or 2

Q.4 Write the general equation for damped harmonic oscillator. Solve it and discuss all thethree features of damping i.e. when damping is small, medium, and high.

Q.5 (a) What is interference of light? What are the necessary conditions for interference?


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(b) How interference pattern is formed in case of Newtons Rings? Drive an expression forthe radius of the dark and bright fingers.

Q.6 (a) Give the Clausius, and Kelvin Planck statements of the second law orthermodynamics. Show that the two statements are equivalent.(b) What are the basic assumptions on which the kinetic theory of gases is developed?

Explain these in brief.Q.7 Write notes on any two of the followings:Lorentz TransformationStanding WavesMaxwell Distribution of molecular velocity

Q.8 Write only the correct answer in the Answer Book. Dont reproduce thequestions.

1. What is the exhaust temperature required to operate a Carnots heat engine at theefficiency of 38%, if the higher temperature is 200 ?a. 20 b. 17 c. 15 d. 38 e. None of these

2. The minimum number of unequal forces whose vector sum can be ZERO is:a. 1b. 2c. 3d. 4e. None of these

3. Entropy of universe during any natural processa. Remains constantb. Increasec. Decrease in internal energy or remain constantd. Increase in temperaturee. None of these

4. Heat energy added to a system under isothermal conditionsa. Work done on the systemb. Increase in internal energyc. Increase in temperatured. Work done by the systeme. None of these

5. Which one of the following properties of waves is not found in both sound waves andradio waves?a. Reflectionb. Interferencec. Diffractiond. Polarizatione. None of these


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6. A man hears a musical sound produced by a tuning for fork. The frequency of the tuningfork, in cycles per second is,a. 4b. 400c. 40000d. 10000

e. None of these7. In sound frequency determination pitch and in light frequency determines a. Speedb. Type of polarizationc. Colourd. None of these

8. The minimum initial velocity requires to take a body, at the surface of the earth, out ofthe gravitational field of the earth is given by,a. (2gRe) b. 2gRe c. 2Reg d. 2Re/g

9. A collision is said to be elastic if,a. Momentum and kinetic energy are both conservedb. Momentum is conserved and kinetic energy changesc. Momentum changes and kinetic energy is conservedd. Momentum and kinetic energy both changee. None of these

10. The object of Michelson and Morley experiment was to find:a. Velocity of lightb. Velocity of earth with respect to other

c. Nature of lightd. All of the abovee. None of the (a), (b), (c)

11. What makes a steel needle float on the top of the water?a. Surface Tensionb. Adhesionc. Viscosityd. Densitye. None of these

12. A gas at pressure of 4 atmospheres is allowed to expand isothermally from a volume of100 cm ^3 to a volume of 400 cm ^3. The new pressure is:a. 16 atmosphereb. 4 atmospherec. 1 atmosphered. None of these

13. Air resistance has an effect on projectiles. Which factor(s) does it influence?a. Speedb. Maximum heightc. Range


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d. All of the abovee. None of the (a), (b) and (c)

14. A container has a small hole in the bottom. Air can go through this hole, but watercannot. This can be best explained by the statement that:a. Water molecules are larger than molecules in the air

b. Water molecules are smaller than molecules in the airc. Water is more viscous than aird. Surface tension of the water prevents it from escapinge. None of these

15. The volume of a given mass of gas will be doubled at atmospheric pressure iftemperature of the gas is changed from 150 to:a. 300 b. 423 c. 573 d. 743 e. None of these

16. If a force moves a body with certain velocity, then the power is:a. Cross product of force and velocityb. Dot product of force and velocityc. Product of force and square of velocityd. Force divided by velocitye. None of these

17. If the distance between a point source of light and a surface is tripled, then intensity ofillumination on the surface will bea. Tripledb. Reduced to 1/2c. Reduced to 1/3

d. Reduced to 1/9e. None of these

18. X and Y are each 6 feet tall. X stands 4ft. from a vertical plane mirror, and Y 8ft. fromthe same mirror. The size of Xs image as compared with Ys is: a. 4 times as greatb. Twice as greatc. The same sized. Twice as smalle. None of these

19. When a body moves at a speed nearly equal to the velocity of lighta. Its mass increasesb. Its length decreasesc. Both (a) and (b) are trued. None of these

20. The average transactional kinetic energy of an atom of a gas is equal to:a. (1/2) KTb. (3/2) KTc. 3 KT


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d. KTe. None of these


IN B.P.S. 17, UNDER THE FEDERAL GOVERNMENT, 2002 Time Allowed: 3 hoursMaximum Marks: 100

PAPER II


Q.1 (a) Extend Gausss theorem to derive poissons equations. Show that Laplacesequation s are Poissons equation s written in an other way.

Consider an isolated uniformly charged spherical conductor. Calculate the Electric intensityat points (i) outside and (ii) inside the sphere.

Q.2 (a) What is a Poynting vector? Evaluate it for an electromagnetic wave.Calculate the flow of electromagnetic energy into a resistor- cylindrical of length L, radius rand resistance across which a potential difference V is applied.

Q.3 (a) Describe triode value and discuss its static and dynamic characteristics.(b) Howa triode value can be used as an amplifier?(c) A triode value has a mutual conductance of 2.5 ma per volt and an anode ac resistanceof 20,000 ohms. Find the load resistance which must b inserted in the anode circuit toobtain a stage gain of 30.

Q.4 (a) Describe a PN junction. Discuss its ampere-volt characteristics. Why there is suddenincrease in the small reverse saturation current at the Breakdown voltage? Write the uses ofZener diode.(b) What are transistors? Draw the 3 types of ten common resistors circuits. Define de alphaand de beta of a transistor.

Q.5 (a) Describe Compton effect and find out the expression for the change in wavelengthwhen an electromagnetic photon strikes a particle an electron of an atom.(b) How much is the maximum change in wavelength in terms of Compton wavelength?(c) An X-ray photon whose initial frequency was 05 1.5(10)^19 Hz emerges from a

collision with an electron, with a frequency of 1.2(10)^19 Hz. How much kinetic energyimported to the electron?

Q.6 (a) What is nuclear fission, fission cross-sections and thresholds? Describe a nuclearreactor.(b) When an atom of ^( 235) U undergoes fission in a Statement reactor, about 200 Mevenergy is liberated. Suppose that a reactor using uranium-235 has an output of 700 MWand is 20% efficient:(i) How many atoms does it consume in one day?


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(ii) What mass of uranium does it consume daily?

Q.7 Write short essay on any TWO of the following:a. Integrated Circuits (ICs) and their role in the advancement of present technologies.b. Isotopes and the uses of radio isotopes.c. Nature of and the experiments which confirm duality behaviour.

Q.8 Write only the correct answer in the Answer Book. Dont reproduce thequestions.

1. Which of the following deals with the properties of matter and energy and their mutualrelationship?a. Chemistryb. Astronomyc. Physicsd. None of these

2. The mass of electron is:a. 1.9 x 10-31 Kgb. 9.1 I x 10-28 gc. Equal to protond. None of these

3. The radius of hydrogen atom is:a. 5.3 x 10 - 10 mb. .53 x 10-10 mc. .053 x 10-10 md. None of these

4. The radioactive substance whose half life is 7 days, decays completely in:a. 14 daysb. 21 daysc. 28 daysd. None of these

5. The spiltting of spectral lines of an element when it radiates is a magnetic field is knownas:a. Induced emissionb. Zeaman effectc. Population inversed. None of these

6. Normally the emitter of a transistor is:a. Reverse biasedb. Forward biasedc. Not biasedd. None of these

7. Fission chain reaction is controlled by introducing rods of:


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a. Graphiteb. Cadmiumc. Borond. None of these

8. The first atomic reactor was introduced by:a. Curieb. Wilsonc. Rutherfordd. None of these

9. Gamma rays waves like:a. Sound wavesb. Beta wavesc. X-raysd. None of these

10. The path Beta particle is:a. Straightb. Circularc. Zig-zagd. None of these

11. Which one is most penetrating?a. -raysb. X-raysc. -raysd. None of these

12. A forward biased diode has resistance:a. Zerob. Infinitec. Equal to reverse biased oned. None of these

13. The reverse current through a semiconductor is due to:a. Majority carriersb. Electronsc. Minority carriersd. None of these

14. The energy of radio waves is greater than:a. Lightb. Microwavesc. X-raysd. None of these

15. Thermal neutrons are:a. At high temperature


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PHYSICS, PAPER - I

TIME ALLOWED: THREE HOURS MAXIMUM MARKS:100

NOTE: (i) Attempt FIVE questions in all including question No. 8 which iscompulsory. All questions carry EQUAL marks. (ii) Extra attempt of any question or any part of the attempted question will not beconsidered (iii) Candidate must draw two straight lines (==================) at theend to separate each question attempted in Answer Books.

Q.1. (a) If , , are the angles that vector r=xi+yj+zk makes with the positive directions

of the coordinate axes, then show that cos 2 + cos 2 + cos 2 = 1 . (6)(b) Find a such that the vectors 2i j+k, i+2j 3k, and 3i+aj+5k are coplanar. (6)(c) If =3x2z y2z3+4x3y+2x 3y5, then find Div. grad F . (8)

Q.2. (a) State and explain Keplers laws of planetary motion. (12) (b) A satellite is placed in a circular orbit with a radius equal to one half the radius of themoons orbit. What is its period of revolution in lunar months (the period of revolution ofmoon)? (8)

Q.3. State Bernoullis theorem and give all necessary conditions. Derive Bernoullis equationfor moving fluids. (4,4,12)

Q.4. (a) What is simple harmonic motion (SHM)? Write the equation for SHM and solve it tofind its time period. (2,4,8) (b) A body oscillates with SHM according to equation: (6)x=(6.12m)cos(8.38 rad/s)t+1.92 rad. Find its time period.

Q.5. (a) What do you understand by diffraction of light? Give all the necessary conditions.Explain diffraction through a single slit and derive an expression for the minimas in thediffraction pattern. (2,4,4,6)(b) Monochromatic light of wavelength 44lnm falls on a narrow slit On screen 2.16m away,the distance between the second minima and the central maxima is 1.62cm. Find the widthof the slit. (4)

Q.6. (a) Explain the terms isothermal and adiabatic processes and calculate the work donein each case. (7,7)(b) Calculate the work done by an external agent in compressing 1.12 mole of oxygen froma volume of 22.4L and 1.32atm. pressure to 153 L at the same temperature. (6)

Q.7. Write notes on any TWO of the following: (10 each)(a) Lorentz transformation(b) Equivalence of mass and energy(c) Production of low temperature


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COMPULSORY QUESTION

8. Write only the correct answer in the Answer Book. Do not reproduce the questions.

(1) A rock is thrown vertically upward with initial speed Vo. Assume a frictional forceproportional to the velocity of rock V, and neglect the buoyant force exerted by air. Theacceleration of the rock is?(a) Always equal to g (b) Equal to g only at the top of the flight (c) Always less than g (d) None of these

(2) In circular motion, the quantity mv/r is:(a) Momentum(b) Acceleration(c) Force(d) None of these

(3) A ball is dropped from a height h. As it becomes off the floor its speed is 80 percent ofwhat it was just before it hit the floor. The ball will rise to a height of most nearly.(a) .80 h(b) .75 h(c) .64 h(d) None of these

(4) A force is said to be conservative if:(a) F.dA=0

(b) F.dr=0(c) Force must be frictional(d) None of these

(5) The kinetic energy of a particle of mass m and momentum p is given by (a) 2m/p(b) p/2m(c) 2m/p(d) None of these

(6) Youngs Modulus is the ration between: (a) Strain and stress(b) Stress and strain(c) Strain and longitudinal stress(d) None of these

(7) In special theory of relativity the Time Dilation applies to:(a) Atomic clocks only(b) Mechanical clocks only(c) Both clocks


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(b) Sound waves(c) Infrared light waves(d) None of these

(16) In sound frequency determines Pitch and in light frequency determines: (a) Speed(b) Type of polarization(c) Colour(d) None of these

(17) The velocity of electromagnetic wave in free space is given by:(a) C 2 = o Eo(b) C = o Eo(c) C= o / Eo(d) None of these

(18) The speed of light in a certain transparent substance is two fifths of its speed in air.

The index of refraction of this substance is:(a) 1.4(b) 2.0(c) 2.5(d) None of these

(19) A thin layer of oil on the surface of water appears coloured because of:(a) Interference(b) Polarization(c) Diffraction(d) None of these

(20) A man is 10 feet away from a plane mirror. His distance from his image is:(a) 20(b) 10(c) 5(d) None of these



PHYSICS, PAPER - II

TIME ALLOWED: THREE HOURS MAXIMUM MARKS:100

NOTE: (i) Attempt FIVE questions in all including question No. 8 which iscompulsory. All questions carry EQUAL marks. (ii) Extra attempt of any question or any part of the attempted question will not beconsidered (iii) Candidate must draw two straight lines (==================) at the


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end to separate each question attempted in Answer Books.

Q.1. Write an expression giving the capacity of parallel plate capacitor and derive anequation giving the energy stored in it. How the capacity changes when it is filled with adielectric material? (4,10,6)

Q.2. (a) Explain Amperes circuital law. Use it to find the magnetic field i n asolenoid. (6,8)(b) A solenoid 1.33cm long and 2.6cm in diameter carries a current of 17.8A. The magneticfield inside the solenoid is 22.4mT. Find the length of the wire forming the solenoid. (6)

Q.3. (a) Explain the term radioactivity. Write the equation for decay rate and find theexpression for half life of radioactive element. How will you find the age of the radioactivesample? (2,3,6,5)(b) A rock is formed to contain 4.2mg of U and 2mg of Pb. Assume that the rock containedno lead at formation, with all the lead now present arising from the decay of uranium. Findage of the rock. The half life of U is 4.47x10 9 years.(4)

Q.4. (a) What is thermionic emission? Name and explain some of its important applications.(4,6)(b) How can you use triode as detector in radio wave receivers? (10)

Q.5. (a) What is P-N junction? Explain its working in forward and reverse biasing conditions.(4,8)(b) Draw bridge circuit for rectification and explain how it rectifies an AC. (8)

Q.6. (a) Explain de Broglie hypothesis and write an equation giving de Broglie wavelength.Give an experiment to prove it. (4,4,6)(b) Calculate the de Broglie wavelength of an electron whose kinetic energy is 120eV. (6)

Q.7. Write notes on any TWO of the following: (10 each)

(a) Paul is exclusion principle (b) Zeeman effect(c) Elementary particles

COMPULSORY QUESTION

Q.8. Write only the correct answer in the Answer Book. Do not reproduce thequestion. (20)

(1) Four equal charges of +10 m C are placed at four corners of a square. The electricintensity at the center of the square is:

(a) Zero NC 1(b) 5 NC 1(c) 2.5 NC 1(d) None of these

(2) A current of 200mA is flowing in a conductor. How many electrons are passingthrough it in one minute?(a) 75X10 20 (b) 750X10 18


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(c) 75X10 15 (d) None of these

(3) A particle having charge q and moving with velocity v enters in the magnetic fieldB at right angles to the field. The force acting on the particle is:(a) Bqv(b) Bq/v(c) Bv/q(d) None of these

(4) Maximum voltage is induced in the conductor when it moves in the magnetic fieldin the direction:(a) Perpendicular to the field(b) Parallel to the field(c) At an angle of 45to the field(d) None of these

(5) Lines of magnetic field have the property:(a) Lines do not terminate at the magnetic poles(b) Lines continue to pass through the bar magnet(c) Both (a) and (b)(d) None of these

(6) Bohr atomic theory cannot explain:(a) The intensity of spectral lines(b) Atomic interaction(c) Both (a) and (b)(d) None of these

(7) Electron-positron annihilation gives out:(a) Alpha-rays(b) Beta-rays(c) Gamma-rays(d) None of these

(8) In photoelectric effect the energy of the photon in excess of work function of themetal is:(a) Absorbed by the metal(b) Reflected back(c) Taken by the emitted electron(d) None of these

(9) The probability that a particle will leak through a potential barrier is known as:(a) Tunnel effect(b) Zeeman effect(c) Quantum effect(d) None of these

(10) A narrow wave group helps to determine accurately, the:


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(a) Position of a particle(b) Momentum of a particle(c) Both (a) and (b)(d) None of these

(11) The relationship between the atomic number (A), mass number (M), and number ofneutrons (N) is:(a) A=MN(b) A=M N(c) A=N M(d) None of these

(12) In 1896, the radioactivity was discovered by:(a) Curies(b) Becqueral(c) Dalton(d) None of these

(13) The emission of one alpha particle from the nucleus of an atom produces a change of:(a) 1 in atomic number(b) 1 in atomic mass(c) 2 in atomic number(d) None of these

(14) Fermions have half integral spin and:(a) Obey exclusion principle(b) Do not obey exclusion principle(c) May or may not obey exclusion principle(d) None of these

(15) The conversion of atoms of a given element into atoms of a different isotope or of adifferent element, as in radioactive disintegration or by nuclear bombardment, isknown as:(a) Radioisotope(b) Transmutation(c) Transformation(d) None of these

(16) According to Band theory of solids, free electrons are present in:(a) Valance band(b) Conduction band(c) Both (a) and (b)(d) None of these

(17) The forbidden energy gap of a material is 0.01eV, the material is:(a) Semiconductor(b) Insulator(c) Conductor(d) None of these


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(18) In a semiconductor which is heavily doped with arsenic, electrons are also called:(a) Majority carriers(b) Minority carriers(c) Fast carriers(d) None of these

(19) Among the vacuum tube devices, the suppresser grid is present only in: (a) Triode(b) Tetrode(c) Pentode(d) None of these

(20) In a p-n-p transistor, the emitter-base junction is always forward biased while thecollector-base junction is reversed biased. As a result, any changes in base current willeffect the:(a) emitter current

(b) base current(c) collector current(d) None of these

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Year 2009

As image.

Year 2010

Physics Paper 2010Paper 1Part II

Q.2 a) define a scalr field,obtain an expression for the Gradient of a scalar field. Why thegradient of a scalar field is vector?

b) Given phi (x,y,z) = X2yz3 (x square y z cube)find grad at phi (1,2,1)


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c) for what values of 'a' ,the vector A = 2i+aj+k and B= 4i -2j-2k are perpendicular.

Q.3 a) Distinguish between Linear and Angular momentum. Explain the law of conservationof angular momentum. Prove that the Angular momentum is constant in the absence ofexternal torque.

b) The angular momentum J ps a particle is given as kj = 8 t powers 4 i- 2 t square j + 12 tcube k. find the torque at t=1

Q.4 a) Discuss in detail the relativity of mass, time and length.b) What is time dilation? Explain with example.c) When we say that a clock in moving frame runs slower than a clock in a stationary frame.What does it mean?

Q.5 a) Differentiate between streamline and turbulent motion of a liquid.b)What is" coefficient of viscosity"? Explain in detail the Stoke's Law applicable indetermining the coefficient of viscosity of a viscous liquid experimentally.c) Why do auto manufactures recommend using different viscosities of engine oil in cold andhot climate,

Q.6 a) what is polarization of light? Explain Polarization by reflection and obtain BrewstarLaw. Also explain the idea of double reflection.b) We wish to use a Quartz sheet (n=1.54) in air as polarizer. Find the polarizing angle andangle of refraction.

Q.7 a) Define internal energy. State and explain First and Third laws of thermodynamics.b) what is heat engine ?Determine the efficiency of the engine if it takes 10,000 J of heatand delivers 2000 J of work per cycle.

Q.8 write note on any TWO:i) centre of massii) diffraction grating and Resolving Poweriii)Production of low temperature.

Physics Paper 2010Paper 2Part II

Q.2 a) State and prove Gauss's law in electrostatics and express the law in differentialforms.b) Find the electricity intensity at a point outside a volume distribution of charge confinedinto a spherical region of radius R.

Q.3 a) State and explain Ampere's law . Derive an expression for the value of 'B' inside asolenoid.


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b) a thin 10 cms long solenoid has a total of 400 turns of wire and carries a current of .20ampere. Calculate the field inside near the centre.(given 0 = 12.57 *10 powers-7 T-m/A )

Q.4 a How a semi conductor diode is used as a half wave and full wave rectifier?b) What are the transistors? Give construction and symbol of PNP and NPN transistor.c) The resistivity of a metal increases with increase in temperature while that of a semiconductor decreases. Explain

Q.5Discuss briefly the wave number of matter and obtain an expression of de Broglie'swavelength for matter waves.b) calculate de Broglie's wavelength of a .20 kg ball moving with a speed of 15m/s.

Q.6 a) Derive Einstein's photoelectric effect on the basis of quantum theory and deriveEinstein's Photoelectric equations.b) calculate the work function of NA in electron volts given that the threshold wavelength is6800. 6.625 * 10-34 J-S

Q.7 a)Define the terms decay constant ,half life and average life as applied to a radioactivesubstance. Find the relation between them.b)The half life of radium is 1590 years . In how many years will one gm of pure elementi) lose one centigramii) be reduced to one centigram

c) Whena nucleus emitsa gamma ray photon ,what happens to its atomic number and itsactual mass.

Q.8 Write notes on any Two:a) self and mutual inductance

b) Pauli's Exclsusion Principlec) Compton Scattering

Paper I

PART I (MCQ)(COMPULSORY)

Q.1. Select the best option/answer and fill in the appropriate box on the Answer Sheet. (20)

(i) If A= 6i-8j, then 4A has the magnitude:(a) 40

(b) 10(c) 20(d) None of these

(ii) Let A= 2i+6j-3k and B= 4i+2j+k then A.B equals:(a) 8i+12j-3k(b) 17(c) 23(d) None of these


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(iii) If V is an operator, then V.V means:(a) Gradient of a Scalar field(b) Curl of a vector field(c) Divergence of a Vector field(d) None of these

(iv) The volume of a parallelepiped bounded by Vectors A,B and C can be obtained from theexpression:(a) ( A x B ).C(b) (A.B)x C(c) ( A x B ) x C(d) None of these

(v) A force acting on a particle is conservative if:(a) It obeys Newton's third law(b) It obeys Newton's second law

(c) It works equals the change in Kinetic energy(d) None of these

(vi) A torque applied to a rigid object always tends to produce:(a) A rotational acceleration(b) A linear acceleration(c) Precision(d) None of these

(vii) When the velocity of a body is constant, its acceleration is:(a) Maximum(b) Zero

(c) Infinityd) None of these

(viii) In the absence of external torque the total angular momentum is:(a) Constant(b) Zero(c) infinity(d) None of these

(ix) The rate of change of Momentum of the particle is:(a) Energy(b) Force(c) Impulse(d) None of these

(x) Constructive and destructive superposition of waves is observed in:(a) Polarisation(b) Interference(c) Diffraction(d) None of these


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(xi) The intensity of a wave is proportional to the square of:(a) Amplitude(b) Time(c) Intensity(d) None of these

(xii) The colours in soap bubbles, oil slick etc. in a thin film is due to:(a) Diffraction(b) Polaristaion(c) Interference(d) None of these

(xiii) For higher resolution, in a diffraction grating, one needs to have:(a) Large number of ruling(b) Small number of ruling(c) No rulings at all

(d) None of these(xiv) To produce interference, the sources must be:(a) Intense(b) Incoherent(c) Coherent(d) None of these(xv) Interference fringes are of:(a) Unequal width(b) Equal width(c) Variable width(d) None of these

(xvi) A Carnot Cycle is:(a) a rectangle on a P-V graph(b) bounded by two isotherms and two adiabatics(c) any four sided process on a P-V graph(d) None of these(xvii) In an Adiabatic process:(a) The temperature of the system remains constant(b) The temperature of the system must change(c) The internal energy(xviii) A Carnot Cycle heat engine operates between 227C and 127 C. Its efficiency is:(a) 44%(b) 20%(c) 79%(d) None of these

(xix) Metals pipe carrying water some times bursts in winter because:(a) Water expands(b) Ice expands when melts(c) Metal contracts more than water


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(d) None of these

(xx) A Fahrenheit thermometer and Celsius thermometer shows the same reading at:(a) 200(b) -40(c) 100(d) None of these


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