Physics Questions

An ideal gas is made of polyatomic molecules. Each of the molecules has three translational, three rotational and f number of vibrational modes. If the ratio of heat capacities Cp/Cv of the gas is 8/7, then the value of f is :

Bob B of mass m at rest is hanging vertically from the ceiling via a massless string of length 10 m, as shown in the figure. Point mass A of mass m travelling horizontally with speed 10 ms⁻¹ hits bob B elastically. The bob B rises h meter after the c

The following table presents the part of the electromagnetic spectrum and their corresponding major applications. The correct option is :

Three identical p-n junction diodes D₁, D₂ and D₃ are connected across a battery as shown in the figure. If the width of the depletion regions of D₁, D₂ and D₃ are W₁, W₂ and W₃, respectively, then the correct option is :

A car travels on a circular racetrack of radius 50 m, which is banked at an angle θ. If the car travels at a speed 10 ms⁻¹, then the wear and tear on its tyres is minimum. Taking the acceleration due to gravity to be 10 ms⁻², the value of θ is :

Consider that an electron is revolving in an excited state of Hydrogen atom with velocity √25.6 × 10⁵ ms⁻¹. The radius of the orbit is x × 10⁻⁹ m. The value of x is : [Take the mass of electron to be 9 × 10⁻³¹ kg, charge of electron = −1.6 × 10⁻¹⁹ C

One mole of an ideal monatomic gas undergoes a cyclic process as shown in the figure. The total heat supplied to the gas is :

An electromagnetic wave travelling in a lossless dielectric medium having a dielectric constant εr = 9, has the electric field, Ex = E₀ sin (kz − 2π × 10⁶t) Vm⁻¹ where E₀ is the amplitude and k is the wave vector. Among the following options, the inc

Consider that σs, kB, b represent Stefan-Boltzmann constant, Boltzmann constant and Wien's displacement law constant, respectively. The dimension of σskB⁻¹b is :

Consider two circuits, (A) and (B), each having two resistors. One of them has a positive temperature coefficient of resistance, +α, while the other one has a negative temperature of coefficient, −α, as shown in the figure. The current through these

In Geiger-Marsden experiment, the number scattered α-particles N(θ) is plotted as a function of scattering angle θ. Which of the following options represent the correct plot ?

Consider a fixed uniformly charged insulating sphere with radius R and total charge +Q. A point charge −q (q << Q) with mass m is released from rest at a distance of 3R from the centre of the charged sphere. When the point charge reaches the surface

A point charge Q is placed inside a cavity within a solid isolated conducting sphere. Consider points A, B and C as shown in the figure, where the magnitudes of the electric fields are EA, EB and EC, respectively. The points B and C are at the same d

A conducting loop of finite resistance lies on the x-y plane. There is a constant magnetic field in the z direction. The area of the loop varies with time t, as A = A₀ (1 + sin t) in appropriate units. The figure that correctly indicates the qualitat

A thin horizontal disc is rotating about a vertical axis passing through its fixed centre O. Its angular momentum is LA and LB computed about points A and B, respectively, with OB = 2 × OA. The value of LA/LB is :

An ac voltage V = 220 sin (2 × 10³t) Volt is applied to a series LCR circuit. Then the current amplitude in this circuit is : (Given : L = 10 mH, C = 25 μF, R = 100 Ω)

The lens combination as shown in the figure, consists of two lenses L₁ and L₂, of the focal lengths +10 cm and −10 cm, respectively. The position of the image formed is :

Consider a spring mass simple harmonic oscillator in one dimension. The mass of the particle is m kg and the spring constant is k Nm⁻¹. At a given instant, the extension of the spring is x meter and the speed of the particle is v ms⁻¹. On the x-v pla

A solid sphere A of radius R and mass M is attached at a point to a smaller solid sphere B of radius r < R and mass m < M. Assume that the line joining their centres lies along the horizontal. The moment of inertia of the system calculated about a ve

One main scale division of a Vernier calliper is equal to 1 mm and the number of divisions on the Vernier scale is 10. When both the jaws touch each other, the Vernier scale shifts to the left of zero of the main scale in such a way that 4th Vernier

A cylindrical cork of uniform density floats in a liquid of density ρ₁. If the cork is depressed slightly and released, it oscillates harmonically with time period T. If the same cork floats in another liquid of density ρ₂, then the similar oscillati

The temperature of a metallic sphere of radius R is increased by a small amount ΔT. If the linear coefficient of thermal expansion of the metal is α, the approximate increase in the volume of the sphere is :

A frictionless circular wire of unit radius is fixed on the horizontal plane. Two point particles of unit mass start moving simultaneously from point A (θ = π/2) with identical uniform angular speeds in opposite directions, and meet again at point B

Consider three media P, Q and R with refractive indices 1, 1.25, and 1.5, respectively. The medium Q having a thickness of 5 cm is placed between extended media P and R as shown in the figure. An object O is placed at the centre of medium Q. If viewe

A unit positive point charge is taken slowly through an infinitesimally thin tube that is inside a charged dielectric sphere of radius R, having uniform positive charge density ρ, as shown in the figure. The initial and final positions of the charge

Which of the following measurements require 'index correction'?

A photon and an electron, each of 20 eV energy, move in free space. The ratio of linear momentum of electron pe to that of photon pPh, pe/pPh is : (Take speed of light = 3 × 10⁸ ms⁻¹, charge of electron = −1.6 × 10⁻¹⁹ C and mass of electron = 9 × 10⁻

A ray of light with wavelength λ is incident on three different photo-electric cells namely 1, 2 and 3. The threshold wavelength of these photo-electric cells are λ₁, λ₂ and λ₃, respectively and the magnitude of stopping potentials of these cells are

In an adiabatic expansion, the temperature of one mole of an ideal monatomic gas (γ = 5/3) decreases from 60 K to 50 K. The work done by the gas in the process is : [Take the universal gas constant as R = 8.3 J mol⁻¹ K⁻¹]

An ideal Zener diode with breakdown voltage of −3V is reverse biased with a negative input voltage Vi = −5V. The magnitude of voltage difference between points B and A is :

Two infinitely long parallel conducting wires A and B carry currents I and 2I, respectively, in the same direction. The wire A has uniform mass per unit length λ and lies on an insulated floor. The wire B is kept fixed at a height h above the floor.

In a solar system, the time-period of revolution of a planet tracing a circular orbit of radius R is proportional to :

Two planets P₁ and P₂ with equal mass have radii R₁ and R₂, respectively, where R₂ = R₁/2. The escape speeds of P₁ and P₂ are v₁ and v₂, respectively. Then v₂/v₁ is :

In the measurement of viscosity of liquids using terminal velocity experiment, spherical balls of same radius but having different densities are used. The variation of the terminal velocity (v) with the ratio of density of spherical ball (σ) to densi

A current I₀ flows through a metallic circular loop of radius r as shown in the figure. Resistance of the segment ABC is half that of ADC. Magnitude of magnetic field at the centre O of the loop is :

Water flows in a streamline motion through a horizontal pipe of circular cross-section as shown in the figure. The pressure difference of water between P and Q is 15 Nm⁻². The area of cross-section at P and Q are 40 cm² and 20 cm², respectively. The

Three identical capacitors P, Q and S, each of the capacitance C, are connected to a battery of voltage V, as shown in the figure. If the energy stored in the capacitor P and total energy stored in the system are UP and UT, respectively, then the rat

A beam of light falls on a metal surface such that photo-electrons are generated. If power of the light source starts to decrease linearly with time t, then variation of the photocurrent I and magnitude of the stopping potential |V| with time is best

Consider the following nuclear reaction : ²³⁸U → ²³⁴Th + ⁴He Take masses of ²³⁸U, ²³⁴Th and ⁴He as 238.050 u, 234.043 u and 4.003 u, respectively. The Q value for the reaction, in keV, is : [Given : 1 u = 931.5 MeV c⁻²]

Consider a particle moving along a straight line, whose position as a function of time is given by s(t) = αt² − βt + γ, where α = 1 ms⁻², β = 6 ms⁻¹ and γ = 5 m. The average speed of the particle, in ms⁻¹, from t = 0 to t = 6 s is :

Consider a long solenoid of length l and radius r. If n is the number of turns per unit length and μ₀ is the permeability of free space, the inductance of the solenoid is :

For sound waves, if the number of nodes for the 5th harmonic of an open-ended pipe is n and that for the 9th harmonic of the same pipe with one of its ends closed is m, the ratio n/m is :

Two identical inductors are connected in two different configurations P and Q, where a time varying current I(t) is flowing, as shown in the figure. The induced emf between points a and b for configuration P is Ep and that for configuration Q is Eq.

The mean free path of molecules in an ideal gas A is half that of another ideal gas B. The diameter of the spherical molecules of gas A is twice the diameter of the molecules of B. If number densities of the gases A and B are nA and nB, respectively,

A particle of mass M moves along a horizontal x axis from x = 0 to x = L. The coefficient of kinetic friction varies as a function of x as μk(x) = μ0 − αx, where μ0, α are constants of appropriate dimensions, so that μk(L) = 0. The total work done by