List of top Physics Questions on Modern Physics asked in IIT JAM

A satellite of mass 10kg, in a circular orbit around a planet, is having a speed 𝑣=200m/s. The total energy of the satellite is _______kJ. (Rounded off to nearest integer)

One mole of an ideal monoatomic gas is heated in a closed container, first from 273K to 303K, and then from 303K to 373K. The net change in the entropy is ______R. (Rounded off to two decimal places) (R is the ideal gas constant)

A ball is dropped from a height ℎ to the ground. If the coefficient of restitution is 𝑒, the time required for the ball to stop bouncing is proportional to:

In a Newton’s rings experiment (using light of free space wavelength 580nm), there is an air gap of height d between the glass plate and a plano-convex lens (see figure). The central fringe is observed to be bright.

The least possible value of d (in nm) is:

The number of atoms in the basis of a primitive cell of hexagonal closed packed structure is:

A crystal plane of a lattice intercepts the principal axes $\overrightarrow𝑎_1, \overrightarrow𝑎_2,$ and  $\overrightarrow{a_3}$ at 3𝑎₁, 4𝑎₂, and 2𝑎₃, respectively. The Miller indices of the plane are:

A projectile of mass m is moving in the vertical x-y plane with the origin on the ground and y-axis pointing vertically up. Taking the gravitational potential energy to be zero on the ground, the total energy of the particle written in planar polar coordinates (r, θ) is (here g is the acceleration due to gravity)

Water from a tank is flowing down through a hole at its bottom with velocity 5 ms^-1. If this water falls on a flat surface kept below the hole at a distance of 0.1 m and spreads horizontally, the pressure (in kNm^-2) exerted on the flat surface is closest to
Given: acceleration due to gravity = 9.8 ms^-2 and density of water = 1000 kgm^-3

A spacecraft has speed 𝑣_𝑠=𝑓𝑐 with respect to the earth, where 𝑐 is the speed of light in vacuum. An observer in the spacecraft measures the time of one complete rotation of the earth to be 48 hours. The value of 𝑓 is (rounded off to two decimal places).

An α particle with energy of 3 MeV is moving towards a nucleus of ⁵⁰Sn. Its minimum distance of approach to the nucleus is 𝑓×10⁻¹⁴ m. The value of 𝑓 is ________ (rounded off to one decimal place).

For a given vector $\vec{F}=-y\hat{i}+z\hat{j}+x^2\hat{k}$ , the surface integral $\int_S(\vec{▽}\times \vec{F}).\hat{r}dS$ over the surface S of a hemisphere of radius R with the centre of the base at the origin is

For the Maxwell-Boltzmann speed distribution, the ratio of the root-mean-square speed (v_rms) and the most probable speed (v_max) is
Given : Maxwell-Boltzmann speed distribution function for a collection of particles of mass m is
$f(v)=(\frac{m}{2\pi k_BT})^{3/2}4\pi v^2\text{exp}(-\frac{mv^2}{2k_BT})$
where, v is the speed and k_BT is the thermal energy.

In the Thomson model of hydrogen atom, the nuclear charge is distributed uniformly over a sphere of radius 𝑅. The average potential energy of an electron confined within this atom can be taken as $V=\frac{e^2}{4{\pi}e_0R}$ . Taking the uncertainty in position to be the radius of the atom, the minimum value of 𝑅 for which an electron will be confined within the atom is estimated to be 𝑓 × 10⁻¹¹ m. The value of 𝑓 is _______ (rounded off to one decimal place). 
Given: The uncertainty product of momentum and position is ℏ = 1×10⁻³⁴ Js ^-1 ,e=1.6 × 10⁻¹⁹C, and $\frac{1}{4{\pi}e_0}$= 9 × 10⁹ Nm2C ⁻²

A container of volume 𝑉 has helium gas in it with 𝑁 number of He atoms. The mean free path of these atoms is 𝜆_He. Another container has argon gas with the same number of Ar atoms in volume 2𝑉 with their mean free path being 𝜆_Ar. Taking the radius of Ar atoms to be 1.5 times the radius of He atoms, the ratio 𝜆_Ar⁄𝜆_He is__________ (rounded off to two decimal places).

For a cubic unit cell, the dashed arrow in which of the following figures represents the direction [220] ?

The state of a harmonic oscillator is given as Ψ =$\frac{1}{ √3}$ 𝜓₀ -$\frac{1}{ √6}$ 𝜓₁+$\frac{1}{ √2}$ 𝜓₂ , where 𝜓₀, 𝜓₁ and 𝜓₂ are the normalized wave functions of ground, first excited, and second excited states, respectively. Which of the following statement(s) is/are true?

A satellite is revolving around the Earth in a closed orbit. The height of the satellite above Earth's surface at perigee and apogee are 2500 km and 4500 km, respectively. Consider the radius of the Earth to be 6500 km. The eccentricity of the satellite's orbit is ________ (Round off to 1 decimal place).

Let (r, $\theta$) denote the polar coordinates of a particle moving in a plane. If $\hat{r}$ and $\hat{\theta}$ represent the corresponding unit vectors, then

A planet of mass m moves in an elliptical orbit. Its maximum and minimum distances from the Sun are R and r, respectively. Let G denote the universal gravitational constant, and M the mass of the Sun. Assuming M >> m, the angular momentum of the planet with respect to the center of the Sun is

A radioactive nucleus has a decay constant $\lambda$ and its radioactive daughter nucleus has a decay constant 10$\lambda$. At time t = 0, N₀ is the number of parent nuclei and there are no daughter nuclei present. N₁(t) and N₂(t) are the number of parent and daughter nuclei present at time t, respectively The ratio $\frac{N_2(t)}{N_1(t)}$ is