JEE Advanced 2021 physics questions with solutions

Showing 1–10 of 26 questions

• Multi-correctdifficultGeometrical opticsprism and thin prism

  For a prism of angle θ = 60°, the refractive indices of the left and right halves are n₁ and n₂ (n₂ ≥ n₁), as shown. The incidence angle i is chosen so that the ray has minimum deviation when n₁=n₂=n=1.5. For n₁=n and n₂=n+Δn, where Δn << n, the emergence angle is e=i+Δe. Which statement(s) is/are correct?

  

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  • Option A

    Δe (in radians) is greater than Δn.

  • Option B

    Δe is proportional to Δn.

  • Option C

    Δe lies between 2.0 and 3.0 milliradians if Δn = 2.8 × 10⁻³.

  • Option D

    Δe lies between 1.0 and 1.6 milliradians if Δn = 2.8 × 10⁻³.

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• NumericmediumCurrent electricityElectrical Instruments: Galvanometer, Ammeter, Voltmeter & Potentiometer

  To measure the internal resistance r₁ of a cell of emf E, a metre bridge of wire resistance R₀ = 50 Ω, a resistance R₀/2, another cell of emf E/2 (internal resistance r) and a galvanometer are connected as shown. If the null point is at ℓ = 72 cm, find r₁ in ohms.

  

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• NumericmediumThermodynamics

  A container holds 1 kg of water in sunlight. The average solar energy received is 700 W m⁻² and is absorbed over an effective area of 0.05 m². Heat loss to the surroundings follows Newton's law of cooling with constant 0.001 s⁻¹. Take the heat capacity of water as 4200 J kg⁻¹ K⁻¹. Find the long-time temperature difference, in °C, between the water and the surroundings.

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• NumericmediumRotational Motioncombined translatory and rotatory motion ,Pure rolling motion

  A thin rod of mass M and length a rotates horizontally about a fixed vertical axis through O with angular velocity Ω. A thin disc of mass M and radius a/4 is pivoted on the rod with its centre a/4 from the free end and rotates about its own vertical axis with angular velocity 4Ω. The total angular momentum about O is (nMΩa²)/48. Find n.

  

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• ParagraphmediumElectrostaticself potential energy and equipotential surface

  Two points charges -Q and +Q√3 are placed in the xy-plane at the origin (0, 0) and a point (2,0), respectively, as shown in the figure. This results in an equipotential circle of radius R and potential V = 0 in the xy-plane with its center at (b, 0). All lengths are measured in meters.

  

  Sub-question 1

  The value of R is meter.

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  Sub-question 2

  The value of b is meter.

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• MCQeasyNuclear physics

  A heavy nucleus Q of half-life 20 min decays by α emission with probability 60% and β emission with probability 40%. Initially there are 1000 Q nuclei. How many α decays occur in the first hour?

  Options

  • Option A

    50

  • Option B

    75

  • Option C

    350

  • Option D

    525

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• NumericmediumSimple Harmonic Motion

  A bob of mass 0.1 kg is attached to a spring of natural length l₀=0.1 m. k₁=0.009 N m⁻¹ for l>l₀ and k₂=0.016 N m⁻¹ for l<l₀. It is released from l=0.15 m. If full period is T=nπ s, find the nearest integer n.

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• Multi-correctmediumRotational Motionangular momentum in pure rotation and its conservation

  A particle of mass M = 0.2 kg is initially at rest in the xy-plane at a point (x = -l, y = -h), where l = 10 m and h = 1m. The particle is accelerated at time t = 0 with a constant acceleration a = 10 m/s² along the positive x-direction. Its angular momentum and torque with respect to the origin, in SI units, are represented by $\vec{L}$ and τ, respectively. î, ĵ and k̂ are unit vectors along the positive x, y and z-directions, respectively. If k̂ = î × ĵ then which of the following statement(s) is(are) correct ?

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  • Option A

    The particle arrives at the point (x = l, y = -h) at time t = 2s

  • Option B

    τ = 2k̂ when the particle passes through the point (x = l, y = -h)

  • Option C

    $\vec{L}$ = 4k̂ when the particle passes through the point (x = l, y = -h)

  • Option D

    τ = k̂ when the particle passes through the point (x = 0, y = -h)

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• NumericmediumPhotoelectric effect and dual nature of matter

  In a photoemission experiment, Kₚ = 2KQ = 2Kᵣ. The same photon source is used for P and Q, but a different source for R. Work functions are 4.0, 4.5 and 5.5 eV, respectively. Find the photon energy used for R, in eV.

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• NumericmediumGravitationSatellites, Orbital Motion & Kepler’s Laws

  Two stars of masses 3Mₛ and 6Mₛ are separated by 9R, where R is the mean Earth-Sun distance and Mₛ is the Sun's mass. They orbit their common centre of mass in circular orbits with period nT, where T is Earth's orbital period. Find n.

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