VIT - Unsolved Physics - 2010

Vit – Past papers: 

Vit – Past papers PHYSICS - UNSOLVED PAPER - 2010

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

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01 A straight wire carrying current i is turned into a circular loop. If the magnitude of magnetic moment associated with it in MKS unit is M, the length of wire will be a. b. c. d. Problem

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02 The ratio of the amounts of heat developed in the four arms of a balance Wheatstone bridge, when the arms have resistances respectively is 3: 30 : 1 : 10 30: 3 : 10 : 1 30: 10 : 1 : 3 30: 1 : 3 : 10 Problem

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Problem 03 An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature ? The temperature of boiling water is 12.6 min 4.2 min 6.3 min 8.4 min

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Problem 04 Magnetic field at the centre of a circular loop of area A is B. The magnetic moment of the loop will be a. b. c. d.

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Problem 05 In Young's double slit experiment, the spacing between the slits is d and wavelength of light used is . If the angular width of a fringe formed on a distance screen is 10, then value of d is 1 mm 0.05 mm 0.03 mm 0.01 mm

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Problem 06 An electric dipole consists of. two opposite charges of magnitude separated by 2.0 cm. The dipole is placed in an external field of . What maximum torque does the field exert on the dipole? How much work must an external agent do to turn the dipole end to end, starting from position of alignment ? a. b. c. d.

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Problem 07 The electron of hydrogen atom is considered to be revolving round a proton in circular orbit of radius with velocity , where .The current i is a. b. c. d.

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Problem 08 In a double slit experiment, 5th dark fringe is formed opposite to one of the slits, the wavelength of light is a. b. c. d.

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Problem 09 Which of the following rays is emitted by a human body? X-rays UV rays Visible rays IR rays

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Problem 10 A proton of mass enters a uniform magnetic field of 1 T at point A as, shown in figure, with a speed of The magnetic field is directed normal to the plane of paper downwards. The proton emerges out of the magnetic field at point C, then the distance AC and the value of angle will respectively be a. b. c. d.

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Problem 11 A neutral water molelcule in its vapour state has an electric dipole moment of magnitude . How far apart are the molecules centres of positive and negative charges? 4 m 4 mm 4 pm

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Problem 12 Figure shows a straight wire of length l carrying current i . The magnitude of magnetic field I produced by the current at point P is*IMG* a. b. c. d.

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Problem 13 Zener diode is used for producing oscillations in an oscillator amplification stabilization rectification

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Problem 14 Two light sources are said to be coherent if they are obtained from two independent point sources emitting light of the same wavelength a single point source a wide source two ordinary bulbs emitting light of different wavelengths

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Problem 15 A small coil is introduced between the poles of an electromagnet so that its axis coincides with the magnetic field direction. The number of turns is n, and the cross-sectional area of the coil is A. When the coil turns through 1800 about its diameter, the charge flowing through the coil is Q. The total resistance of the circuit is R. What is the magnitude of the magnetic induction? a. b. c. d.

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Problem 16 The attenuation in optical fibre is mainly due to absorption scattering neither absorption nor scattering Both (a) and (b)

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Problem 17 An arc of radius r carries charge. The linear density of charge is and the arc subtends an angle at the centre. What is electric potential at the centre? a. b. c. d.

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Problem 18 Sinusoidal carrier voltage of frequency 1.5 MHz and amplitude 50 V is amplitude modulated by sinusoidal voltage of frequency 10 kHz producing 50% modulation. The lower and upper side-band frequencies iri kHz are 1490, 1510 1510, 1490

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Problem 19 resistors are connected in series. This connection is connected with a battery of 2.4 V. When a voltmeter of resistance is connected across resistor, then the reading of the voltmeter will be 1.6 V 1.0 V 1.2 V 2.0 V

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Problem 20 In space charge limited region, the plate current in a diode is 10 mA for plate voltage 150 V. If the plate voltage is increased to 600 V, then the plate current will be 10 mA 40 mA 80 mA 160 mA

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Problem 21 Light of wavelength strikes a photo-sensitive surface and electrons are ejected With kinetic energy E. If the kinetic energy is to be increased to 2E, the wavelength must be changed to where a. b. c. d.

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Problem 22 The maximum velocity of electrons emitted from a metal surface is v, when frequency of light falling on it is f. The maximum velocity when frequency becomes 4f is 2v > 2v > 2v between 2v and 4v

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Problem 23 The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on and a saturation photo-current is recorded. An electric field is switched on which has a vertically downward direction, then the photo-current will increase the kinetic energy of the electrons will increase the stopping potential will decrease the threshold wavelength will increase

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Problem 24 A cylindrical conductor of radius R carries a current i . The value of magnetic field at a point which is distance inside from the 4 surface is 10 T. The value of magnetic field at point which is 4R distance outside from the surface a. b. c. d.

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Problem 25 The power of a thin convex lens is 5.0 D. When it is placed in a liquid of refractive index then it behaves as a concave lens of focal length 100 cm. The refractive index of the liquid will be 5/3 4/3 5/4

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Problem 26 Find the value of magnetic field between plates of capacitor at a distance 1 m from centre, where electric field varies by . 5.55 T

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Problem 27 Using an AC voltmeter the potential difference in the electrical line in a house is read to be 234 V. If line frequency is known to be 50 cycles/s, the equation for the line voltage is a. b. c. d.

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Problem 28 There are a 25 W - 220 V bulb and a 100 W - 220 V line. Which electric bulb will glow more brightly? 25 W bulb 100 W bulb Both will have equal incandescence Neither 25 W nor 100 W bulb will give light

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Problem 29 Silver has a work function of 4.7 eV . When ultraviolet light of wavelength 100 nm is incident upon it, potential of 7.7 V is required to stop photoelectrons from reaching the collector plate. The potential required to stop electrons when light of wavelength 200 nm is incident upon silver is 1.5 V 1.85 V 1.95 V 2.37 V

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Problem 30 Two particles X and Y having equal charges, after being accelerated through the. Same potential difference, enter a region of uniform magnetic field and describe circular paths of radii respectively. The ratio of masses of X and Y is a. b. c. d.

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Problem 31 According to the Bohr's theory of hydrogen atom, the speed of the electron, energy and ~ the radius of its orbit vary with the principal quantum number n, respectively, as a. b. c. d.

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Problem 32 In the hydrogen atom, the electron is making . If the radius of the orbit is , then magnetic field produced at the centre of the orbit is 140 T 12.5 T 1.4 T 0.14 T

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Problem 33 Two identical light sources emit light of same wavelength . These light rays will exhibit interference if their phase differences remain constant their phases are distributed randomly their light intensities remain constant their light intensities change randomly

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Problem 34 In Meter bridge or Wheatstone bridge for measurement of resistance, the known and the unknown resistances are interchanged. The error so removed is end correction index errror due to temperature effect random error

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Problem 35 A fish, looking up through the water, sees the outside world contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12 cm below the surface of water, the radius of the circle in centimetre is a. b. c. d.

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Problem 36 Radio waves diffract around building although light waves do not. The reason is that radio waves travel with speed larger than c have much larger wavelength than light carry news are not electromagnetic waves

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Problem 37 In the Bohr model of a hydrogen atom, the centripetal force is furnished by the coulomb attraction between the proton and the electron. If ao is the radius of the ground state orbit, m is the mass and e is charge on the electrun and 1:0 is the vacuum permittivity, the speed of the electron is 0

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Problem 38 A potential difference of 2V is applied between the opposite faces of a Ge crystal plate of area and thickness 0.5 mm. If the concentration of electrons in Ge is and mobilities of electrons and holes are respectively, then the current flowing through the plate will be 0.25 A 0.45 A 0.56 A 0.64 A

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Problem 39 An AM wave has 1800 W of total power content. For 100% modulation the carrier should have power content equal to 1000 W 1200 W 1500 W 1600 W

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Problem 40 Two light rays having the same wavelength in vacuum are in phase initially. Then the first ray travels a path through a medium of refractive index while the second ray travels a path of length through a medium of refractive index The two waves are then combined to observe interference. The phase difference' between the two waves is a. b. c. d.

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