SECTION – I (Total Marks : 50) Single Correct Answer Type There are five parts in this question. Four choices are given for each part and one of them is correct. Indicate you choice of the correct answer for each part in your answer-book by writing the letter (a), (b), (c) or (d) whichever is appropriate

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01 In the case of forward biasing of p-n junction, which one of the following figures correctly depicts the direction of flow of carriers? a. b. c. d. Problem

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Problem 02 Distance between body centered atom and a corner atom in sodium (a = 4.225 Å) is 2.99 Å 2.54 Å 3.66 Å 3.17 Å

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Problem 03 What is the respective number of and - particles emitted in the following radioactive decay? 8 and 8 8 and 6 6 and 8 6 and 6.

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Problem 04 The binding energies per nucleon for a deuteron and an -particle are x 1 and x 2 respectively. The energy Q released in the reaction 2 H 1 + 2 H 1 4He 2 + Q, is 4( x 1 + x 2 ) 4( x 1 - x 2 ) 2( x 2 – x 1 ) 2( x 1 + x 2 )

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Problem 05 The count rate of a Geiger Muller counter for the radiation of the a radioactive material of half-life of 30 minutes decreases to 5 second -1 after 2 hours. The initial count rate wave 80 second –1 625 second -1 20 second -1 25 second -1 .

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Problem 06 An electron makes a transition from orbit n = 4 to the orbit n = 2 of a hydrogen atom. What is the wavelength of the emitted radiations ? (R = Rydberg’s constant ) a. b. c. d.

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Problem 07 When a hydrogen atom is raised from the ground state to an excited state, Both K.E. and P.E. increase Both K.K. and P.K. decrease The P.E. decrease and K.E. increases The P.E. increase and K. E. decrease

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Problem 08 In good conductors of electricity, the type of bonding that exists is Metallic Vander Waals Ionic Covalent.

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Problem 09 The figure represents the observed intensity of X-rays emitted by an X-ray tube, as a function of wavelength. The sharp peaks A and B denote A and B denote What radiations Characteristic radiations Band spectrum Continuous spectrum

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Problem 10 An electron of mass m, when accelerated through a potential difference, V, has de Broglie wavelength The de Broglie wavelength associated with a proton of mass M accelerated through the same potential difference, will be a. b. c. d.

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Problem 11 A charge q is placed at the center of the line joining two exactly equal positive charges Q. The system of three charges will be in equilibrium, if q is equal to -Q Q/2 -Q/4 +Q.

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Problem 12 If we consider electrons and photons of same wavelength, then they will have same Momentum Angular momentum Energy Velocity.

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Problem 13 There is electric field E in x-direction. If the work done on moving a charge of 0.2 C through a distance of 2 m along a line making an angle 60 0 with x -axis is 4 J, then what is the value of E? 5 N/C 20 N/C N/C 4 N/C.

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Problem 14 Two metallic spheres of radii 1 cm and 2 cm are given charges 10-2 C and 5 x 10-2C respectively If they are connected by a conducting wire, the final charge on the smaller sphere is 3 x 10 -2 C 4 x 10 -2 C 1 x 10 -2 C 2 x 10 -2 C

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Problem 15 In the network shown in the figure, each of the resistance is equal to 2 . The resistance between the points A and B is 3 4 1 2

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Problem 16 Two wires of the same metal have same length, but their cross-sections are in the ratio 3 : 1. They are joined in series. The resistance of thicker wire is 10 . The total resistance of the combination will be 40 100 5/2 40 /3 .

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Problem 17 A heating coil is labeled 100 W. 220 V. the coil is cut in half and the two pieces are joined in parallel. To the same source. The energy now liberated per second is 200 J 400 J 25 J 50 J.

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Problem 18 For measuring temperatures in the range of 2000 to 2500 0 C, we should employ Gas thermometer Platinum-rhodium thermometer Barometer Pyrometer.

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Problem 19 A straight line conductor of length 0.4 m is moved with a speed of 7 m/s perpendicular to a magnetic filed of intensity 0.9 Wb /m 2 . the induced e.m.f . across the conductor is 5.04 V 25.2 V 1.26 V 2.52 V.

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Problem 20 The work done in turning a magnet of magnetic moment M by an angle of 90 0 from the meridian, is n times the corresponding work done to turn it through an angle of 60 0 . The value of n is given by 1/2 1/4 2 1.

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Problem 21 When the key K is pressed at time t = 0, then which of the following statement about the current I in the resistor AB of the given circuit is true ? I oscillates between 1 mA and 2 mA At t = 0, I = 2 mA and with time it goes to 1 mA I = 1 mA at all t I = 2 mA at all t.

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Problem 22 Exposure time of camera lens at f /2.8 setting is 1.200 second. The correct time of exposure at f /5.6 is 0.20. second 0.40 second 0.02 second 0.04 second.

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Problem 23 The dimension of RC is Square of time Square of inverse time Time Inverse times

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Problem 24 The figure indicates the energy level diagram of an tom and the origin of six spectral lines in emission (e.g. line no. 5 arises from the transition from level B to A). which of the following spectral lines will also occur in the absorption spectrum? 4,5,6 1,2, 3, 4, 5, 6 1, 2, 3 1, 4, 6.

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Problem 25 A star, which is emitting radiation at a wavelength of 5000 Å, is approaching the earth with a velocity of 1.5 x 104 m/s. The change in wavelength of the radiation as received on the earth is 25 Å 100 Å zero 2.5 Å

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Problem 26 A lens is placed between a source of light and a wall. It forms images of area A 1 and A 2 on the wall, for its two different positions. The area of the source of light is a. b. c. d.

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Problem 27 In an A.C. circuit, the current flowing is amperes and the potential difference is V = 200 sin (100t) volts. The power 20 W 0 W 1000 W 40 W.

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Problem 28 An ideal Carnot engine, whose efficiency is 40%, receives heat at 500 K. If its efficiency is 50% then the intake temperature for the same exhaust temperature is 800 K 900 K 600 K 700 K

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Problem 29 Heat is flowing through two cylindrical rods of the same material. The diameters of the rods are in the ratio 1 : 2 and the lengths in the ratio 2 : 1. If the temperature difference between the ends is same, then ratio of the rate of flow of heat through them will be 2 : 1 8 : 1 1 : 1 1 : 8

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Problem 30 Percentage errors in the measurement of mass and speed are 2% and 3 % respectively. The error in the estimate of kinetic energy obtained by measuring mass and speed will be 8% 2% 12 % 10%

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Problem 31 An oscillator is nothing but an amplifier with positive feed back negative feed back voltage gain no feed back.

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Problem 32 A source of sound gives 5 beats per second, when sounded with another source of frequency 100 second -1 . The second harmonic of the source, together with a source of frequency 205 sec -1 gives 5 beats per second. What is the frequency of the source? 105 Second -1 205 Second -1 95 Second -1 100 Second -1

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Problem 33 A hospital uses ultrasonic scanner to locate tumors in a tissue. The operating frequency of the scanner is 4.2 MHz The speed of sound in a tissue is 1.7 km/s. The wavelength of sound in the tissue is close to 4 x 10 -3 m 8 x 10 -3 m 4 x 10 -4 m 8 x 10 -4 m

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Problem 34 In a simple harmonic motion, when the displacement is one-half the amplitude, what fraction of the total energy is kinetic? 1/2 3/4 zero 1/4

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Problem 35 A beaker full of hot water is kept in a room. If it cools from 80 0 C to 75 0 C in t 1 minutes, from 750C to 700C in t2 minutes and from 70 0 C to 65 0 C in t 3 minutes, then t 1 < t 2 < t 3 t 1 > t 2 > t 3 t 1 = t 2 = t 3 t 1 < t 2 = t 3 .

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Problem 36 The length of a son meter wire AB is 100 cm. Where should the two bridges be placed from A to divide the wire in 3 segments whose fundamental frequencies are in the ratio of 1 : 2 : 3? 60 cm and 90 cm 30 cm and 60 cm 30 cm and 90 cm 40 cm and 80 cm.

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Problem 37 The earth (mass = 6 x 10 24 kg) revolves around the sun with an angular velocity of 2 x 10 -7 rad /s in a circular orbit of radius 1.5 x 10 8 km. The force exerted by the sun on the earth, in Newton, is 36 x 10 21 27 x10 39 zero 18 x 10 25 .

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Problem 38 Two particles of equal mass go around a circle of radius R under the action of their mutual gravitational attraction The speed v of each particle is a. b. c. d.

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Problem 39 the mass number or He is 4 and that of sulphur is 32. The radius of sulphur nucleus is large than that of helium by the factor of 4 2 8 d.

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Problem 40 The ABC is a triangular plate of uniform thickness. The sides are in the ratio shown in figure. I .AB I BC and I CA are the moments of inertia of the plate about AB, BC and CA respectively. Which one of the following relations is correct? I AB + I BC = I CA I CA is maximum I AB > I BC I BC > I AB .

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Problem 41 The water drop falls at regular intervals from a tap 5 m above ground. The third drop is leaving the tap at instant the first drop touches the ground. How far above the ground is the second drop is that instant? 3.75 m 4.00 m 1.25 m 2.50 m.

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Problem 42 A simple pendulum with a bob of mass m oscillates from A to C and back to A such that PB is H. If the acceleration due to gravity is g, then the velocity of the bob as it passes through B is a. MgH b. c. zero d. 2gH.

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Problem 43 If the cold junction of a thermo- couple is kept at & the hot junction is kept at , then the relation between neutral temperature & temperature of inversion is a. b. c. d.

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Problem 44 Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature , the power received by a unit surface ,( normal to the incident ray) at a distance R from the center of the sun is, ( is Stefan's constant) a. b. c. d.

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Problem 45 In the energy band diagram of a material shown below, the open circles & filled circles denote holes & electron respectively. The material is An insulator A metal An n-type semiconductor An p-type semiconductor

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Problem 46 The potential energy between two atoms, in a molecule, is given by where a and b are positive constants and x is the distance between the atoms. The atom is in stable equilibrium, when a. b. c. d.

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Problem 47 the position vector of a particle is The velocity of the particle is directed towards the origin directed away from the origin parallel to the position vector perpendicular to the position vector.

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Problem 48 What is the torque of the force acting at the point m about origin? a. b. c. d.

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Problem 49 Which of the following is a dimensional constant? Relative density Gravitational constant Refractive index Passions ratio.

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Problem 50 The angular speed of a fly-wheel making 120 revolutions/minute is 4 rad /s 4 2 rad /s rad /s 2 rad /s.

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