JEE Mains 2014 physics questions with solutions

Showing 1–10 of 21 questions

• MCQmediumUnit dimension and error

  A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it?

  Options

  • Option A

    A screw gauge having 100 divisions in the circular scale and pitch as 1 mm.

  • Option B

    A screw gauge having 50 divisions in the circular scale and pitch as 1 mm.

  • Option C

    A meter scale.

  • Option D

    A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale and main scale has 10 divisions in 1 cm.

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• MCQmediumProperties of solid and fluid

  The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is : (For steel Young's modulus is 2 ×10¹¹ N m⁻² and coefficient of thermal expansion is 1.1 ×10⁻⁵ K⁻¹)

  Options

  • Option A

    2.2 ×10⁷ Pa

  • Option B

    2.2 ×10⁶ Pa

  • Option C

    2.2 ×10⁸ Pa

  • Option D

    2.2 ×10⁹ Pa

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• MCQmediumCurrent electricityCells, Maximum Power & Heating Effect

  In a large building, there are 15 bulbs of 40W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW. The voltage of the electric mains is 220 V. The minimum capacity of the main fuse of the building will be :

  Options

  • Option A

    8 A

  • Option B

    10 A

  • Option C

    12 A

  • Option D

    14 A

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• MCQmediumProperties of solid and fluid

  Water bubbles of radius R form at the bottom of a vessel and detach when the circular contact radius with the bottom is r. For r ≪ R, surface tension T and water density ρw, find r just before detachment. Image

  Options

  • Option A

    R²√(ρw g/T)

  • Option B

    R²√(3ρw g/T)

  • Option C

    R²√(2ρw g/(3T))

  • Option D

    R²√(ρw g/(6T))

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• MCQmediumUnit dimension and error

  The diode current-voltage relation is I = [exp(1000 V/T) - 1] mA, with V in volts and T in kelvin. At T=300 K the measured current is 5 mA. If V has an uncertainty ±0.01 V, find the resulting current uncertainty.

  Options

  • Option A

    0.5 mA

  • Option B

    0.05 mA

  • Option C

    0.2 mA

  • Option D

    0.02 mA

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• MCQmediumGeometrical opticslens and combination lens,silvered lens

  A thin convex lens made from crown glass (μ = 3/2) has focal length f. When measured in two different liquids of refractive indices 4/3 and 5/3, it has focal lengths f₁ and f₂ respectively. The correct relation between the focal lengths is:

  Options

  • Option A

    f₂ > f and f₁ becomes negative

  • Option B

    f₁ and f₂ both become negative

  • Option C

    f₁ = f₂ < f

  • Option D

    f₁ > f and f₂ become negative

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• MCQmediumWave Motion

  A pipe of length 85 cm is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below 1250 Hz. The velocity of sound in air is 340 m s⁻¹.

  Options

  • Option A

    12

  • Option B

    8

  • Option C

    6

  • Option D

    4

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• MCQmediumAtomic Structure and X-rays

  Hydrogen ¹₁H, deuterium ²₁H, He⁺ and Li²⁺ each have one electron. For the transition n = 2→1, let the emitted wavelengths be λ₁, λ₂, λ₃ and λ₄, respectively. Which relation is correct?

  Options

  • Option A

    λ₁ = λ₂ = 4λ₃ = 9λ₄

  • Option B

    λ₁ = 2λ₂ = 3λ₃ = 4λ₄

  • Option C

    4λ₁ = 2λ₂ = 2λ₃ = λ₄

  • Option D

    λ₁ = 2λ₂ = 2λ₃ = λ₄

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• MCQmediumPhotoelectric effect and dual nature of matter

  Radiation corresponding to the hydrogen transition 3→2 falls on a metal and produces photoelectrons. These electrons enter a magnetic field of 3 × 10⁻⁴ T. If the circular-path radius of the fastest electron is 10 mm, find the work function of the metal.

  Options

  • Option A

    0.8 eV

  • Option B

    1.6 eV

  • Option C

    1.8 eV

  • Option D

    1.1 eV

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• MCQmediumSimple Harmonic Motion

  A particle moves with simple harmonic motion in a straight line. In first τ s, after starting from rest it travels a distance a, and in next τ s it travels 2a, in same direction, then :

  Options

  • Option A

    amplitude of motion is 3a

  • Option B

    time period of oscillations is 8τ

  • Option C

    amplitude of motion is 4a

  • Option D

    time period of oscillations is 6τ

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