amu –Past papers: amu –Past papers PHYSICS- UNSOLVED PAPER - 2002
SECTION – I: SECTION – I 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
Problem: 01 Suitable impurities are added to a semiconductor depending on its use. This is due to : Increase its electrical resistivity Increase its electrical conductivity Increase its life Enable it to tolerate higher voltage Problem
Problem: 02 When are electron and a position at rest are annihilated, then the number of photons produced is : One Two Four Any arbitray number Problem
Problem: Problem 03 A convex lens of focal length 20 cm produces a real image twice the size of the object. Then the distance of the object from the lens is : 10 cm 20 cm 30 cm 40 cm
Problem: Problem 04 The separation between the plates of a parallel plate capacitor is d and area of each plate is A, when a slab of material of dielectric constant K and thickness t is introduced between the plates, the capacitance becomes : a. b. c. d.
Problem: Problem 05 When a potential difference V is applied across a conductor at temperature T, the thermal speed of electrons is proportional to : T V O
Problem: Problem 06 If the electron in hydrogen atom jumps from third orbit to second orbit, the wavelength of the emitted radiation is given by a. b. c. d.
Problem: Problem 07 In Young’s double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is dipped in water of refractive index 4/3, without disturbing the arrangement, the new fringe width will be : 0.30 mm 0.40 mm 0.53 mm 0.2 m
Problem: Problem 08 The final image formed by a microscope is : Virtual and magnified Real and magnified Real and diminished Virtual and diminished
Problem: Problem 09 A 10 thick wire is stretched so that its length becomes 3 times. Then the new resistance of the wire is : 10 30 90
Problem: Problem 10 Five resistance have been connected in the manner shown in figure. The equivalent resistance between points X and Y will be equal to : 10 20 60
Problem: Problem 11 Eddy currents may be reduced by using : Laminated cores of steel Laminated core of soft iron Thick piece of cobalt Thick piece of nickel
Problem: Problem 12 The magnetic energy stored in an inductor coil varies with magnetic field B B 2 B 0
Problem: Problem 13 The specific resistance of wire : Varies with its length Varies with its cross section Varies with its mass Is independent of length, cross section and mass of the wire
Problem: Problem 14 Retentively is maximum for : Steel Soft iron Copper Silver
Problem: Problem 15 The charactivity is maximum for: Amplitude Velocity Frequency wavelength
Problem: Problem 16 The focal length of a concave mirror is : Maximum for red colour Maximum for violet colour Maximum for yellow colour Same for all colours
Problem: Problem 17 A force F is applied on a body and it moves with a velocity , the power will be : F. F. 2
Problem: Problem 18 For the same kinetic energy, the momentum is maximum for : An electron A proton A deutron An particle
Problem: Problem 19 Four spheres each of diameter 2a and mass M are placed with their centers on the four corners of a square of side b. The moment of inertia of the system about any side of the square will be : Ma 2 + 2Mb 2 Ma 2 + Mb 2 Ma 2 + 4Mb 2 Ma 2 + 16Mb 2
Problem: Problem 20 A ring of radius r and mass m rotates about an axis passing through its centre and perpendicular to its plane, its kinetic energy is : mr mr 2 mr 2 2 mr 2 2
Problem: Problem 21 If the speed of the rotation of earth increases, then the weight of the body. Increases Decreases Remains unchanged May increases or decrease
Problem: Problem 22 An organ pipe P 1 closed at one end and vibrating in its first overtone and another pipe P 2 open at both ends vibrating in its second overtone are in resonances. The ratio of length of pipes P 1 and P 2 is : 1 1/2 1/3 3/4
Problem: Problem 23 The equation of a wave traveling in a string is given as y = 3 cos (100t -x). Its wavelength is : 3 cm 100 cm 2 cm 5 cm
Problem: Problem 24 A star is moving away from the earth with a velocity of 10 5 m/s. The shift in the spectral line of wavelength 5700 Å as observed on the earth is : 0.75 Å 1.75 Å 1.9 Å 2.01 Å
Problem: Problem 25 Two sound wave are , the phase difference between the two waves is : /2 /4 0
Problem: Problem 26 The velocity of sound in air is not affected by changes in : Moisture contents in air Temperature of air The atmospheric pressure The composition of air
Problem: Problem 27 The velocity of light in a medium of refractive index 3/2 is : 2 x 10 8 m/s 4 x 10 8 m/s 5 x 10 5 m/s 9 x 10 5 m/s
Problem: Problem 28 The image formed by a convex mirror is : Virtual, erect and diminished Virtual, erect and enlarged Real, inverted and diminished Real, inverted and enlarged
Problem: Problem 29 In a reflecting astronomical telescope, parabolic mirrors are used because they are free from” : Spherical aberration Chromatic aberration Spherical and chromatic aberration both No aberration
Problem: Problem 30 To remove the chromatic aberration, combination of lens should be such that : F R + F V = 0 R R + F V F R < F V F R – F V = 0
Problem: Problem 31 For a long cylindrical source of light, the illuminance E on a screen varies with distance r as : E r -2 E r -1 E r 0 E r 2
Problem: Problem 32 The radius of curvature of curved surface of a plano -convex lens is 15 cm and refractive index of lens material is 1.6. The power of the lens will be : 1.66 D 4 D - 1.0 D - 3.75 D
Problem: Problem 33 A beam of monochromatic blut light of wavelength 4200 Å in air travels in water (refractive index 4/3) its wavelength in water will be : 2800 Å 3150 Å 4000 Å 5600 Å
Problem: Problem 34 Rays of light fall on a glass plate of refractive index . If the angle between reflected and refracted rays is 90 0 , then the angel of incidence is : sin -1 ( ) cos -1 ( ) tan -1 ( ) tan -1 (1/ )
Problem: Problem 35 A plane glass slab is placed over letters of different colours which letters appears to be raised most : Red Violet Yellow All coloured letters appear equally raised
Problem: Problem 36 When an ideal gas is heated at constant pressure, the fraction of the heat energy supplied, which increases the internal energy of the gas, is : a. b. c. d.
Problem: Problem 37 The second law of thermodynamics is concerned with the : Conservation of energy Conservation of number of holes Transformation of heat energy into work Conservation of temperature
Problem: Problem 38 At which of the following temperature would the molecules of a gas have twice, the average kinetic energy they have at 20 0 C ? 313 0 C 373 0 C 393 0 C 586 0 C
Problem: Problem 39 An iron piece falls from a height of 1 km on the ground. If all the energy is converted into heat, the temperature of the iron piece will be (specific heat of iron = 0.1kcal/kg 0 C) : 0.233 0 C 2.33 0 C 32.8 0 C 233 0 C
Problem: Problem 40 If a given mass of gas occupies a volume 100m 3 at one atmospheric pressure and temperature of 100 0 C, What will be its volume at 4 atmospheric pressure the temperature being the same : 25 cm 3 0 50 cm 3 5 cm 3
Problem: Problem 41 Work done by a system is zero in : Isothermal process Adiabatic process Isochoric process Isobaric process
Problem: Problem 42 1 mole of a monoatomic gas is first heated at constant volume at 100 0 C. The change in internal energy of the gas is u 1 . Next it is heated at constant pressure at 100 0 C, the change in internal energy of the gas is U 2 . Then the ratio : 1 uncertain
Problem: Problem 43 If the degrees of freedom of a gas are f then the ratio of its specific heats is given by : 1+ 1 - 1 + 1-
Problem: Problem 44 In bringing an electron towards another electron, electrostatic potential energy of system : Decreases Increases Remains unchanged Becomes zero
Problem: Problem 45 Viscosity is most closely related to : Friction Adhesive molecular force Cohesive molecular force Bernoulli's theorem
Problem: Problem 46 The substances which are repelled by a magnet are called : Diamagnetic substances Paramagnetic substances Ferromagnetic substance Super magnetic substance
Problem: Problem 47 The time constant of L-R circuit is : LR
Problem: Problem 48 In a full wave rectifier, the rms value of AC component of the waves : Equal to DC value More than DC value Less than DC value Zero
Problem: Problem 49 The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volts is : a. b. c. d.
Problem: Problem 50 According to Bohr’s theory the relation between principal quantum number n and radius (r) of orbit : a. b. c. d.
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