List of top Physics Questions

Five gas molecules chosen at random are found to have speeds of 500, 600, 700, 800 and 900 m/s.
Given that A + B = R and A = B = R. What should be the angle between A and B?
A body moves in a circular orbit of radius R under the action of a central force. Potential due to the central force is given by V(r)=kr (where k is a positive constant). Period of revolution of the body is proportional to
A thin but rigid semicircular wire frame of radius r is hinged at O and can rotate in its own vertical plane. A smooth peg P starts from O and moves horizontally with constant speed v₀, lifting the frame upwards as shown in the figure. Find the angular velocity ω of the frame when its diameter makes an angle of 60^∘ with the vertical. \includegraphics[width=0.5\linewidth]34.png
A long, hollow conducting cylinder is kept coaxially inside another long, hollow conducting cylinder of larger radius. Both the cylinders are initially electrically neutral.
Two equal heavy spheres, each of radius r, are in equilibrium within a smooth cup of radius 3r. The ratio of reaction between the cup and one sphere and that between the two spheres is \includegraphics[width=0.5\linewidth]32.png
A telescope has an objective lens of 10 cm diameter and is situated at a distance of one kilometer from two objects. The minimum distance between these two objects which can be resolved by the telescope, when the wavelength of light is 5000AA, is of the order of
During vaporisation: I. change of state from liquid to vapour state occurs. II. temperature remains constant. III. both liquid and vapour states coexist in equilibrium. IV. specific heat of substance increases. Correct statements are
Hydrogen (H), deuterium (D), singly ionized helium (He⁺) and doubly ionized lithium (Li²+) all have one electron around the nucleus. Consider n=2 to n=1 transition. The wavelengths of emitted radiations are lambda₁, lambda₂, lambda₃ and lambda₄ respectively. Then approximately
A coil is suspended in a uniform magnetic field with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; it is very difficult to stop. But if an aluminium plate is placed near the coil, it stops. This is due to
A tuning fork of frequency 392 Hz resonates with 50 cm length of a string under tension T. If the mass of the string is decreased by 2%, keeping the tension constant, the number of beats heard when the string and the tuning fork are made to vibrate simultaneously is
A particle of mass m moving in the x-direction with speed 2v is hit by another particle of mass 2m moving in the same direction with speed v. If the collision is perfectly inelastic, the percentage loss in the energy during the collision is close to
In the formula X = 3YZ², X has dimensions of capacitance and magnetic induction respectively. The dimensional formula of Y in MKSA system is
Two long, straight, parallel wires carry steady currents I and -I respectively. The distance between the wires is d. At a certain instant of time, a point charge q is at a point equidistant from the two wires. The instantaneous velocity v is perpendicular to this plane. The magnitude of the force due to the magnetic field acting on the charge is
A sonometer wire resonates with a given tuning fork forming standing waves with five antinodes between the two bridges when a mass of 9 kg is suspended from the wire. When this mass is replaced by a mass M, the wire resonates with the same tuning fork forming three antinodes for the same position of the bridges. The value of M is
A coil of inductance 300 mH and resistance 2Ω is connected to a source of voltage 2 V. The current reaches half of its steady state value in
A charged particle moves perpendicular to a magnetic field. Then
After two hours, one-sixteenth of the starting amount of a certain radioactive isotope is remained undecayed. The half-life of the isotope is
What is the minimum energy required to launch a satellite of mass m from the surface of a planet of mass M and radius R in a circular orbit at an altitude of R?
An electron beam is accelerated by a potential difference $V$ to hit a metallic target to produce $X-$rays. It produces continuous as well as characteristic $X$-rays. If $\lambda_{\text{min}}$ is the smallest possible wavelength of $X$-ray in the spectrum, the variation of $\log \, \lambda_{\text{min}}$ with log $V$ is correctly represented in :
An object is thrown vertically upward with a speed of $30\, m/s$. The velocity of the object half-a-second before it reaches the maximum height is
A planet of mass $m$ moves in an elliptical orbit around an unknown star of mass $M$ such that its maximum and minimum distances from the star are equal to $r_1$ and $r_2$ respectively. The angular momentum of the planet relative to the centre of the star is
Which of the following is emitted when $^{239}_{94} Pu$ decays into $^{235}_{92}U$ ?
Consider a solenoid carrying current supplied by a DC source with a constant emf containing iron core inside it. When the core is pulled out of the solenoid, the change in current will
A thermocol box has a total wall area (including the lid) of $1.0 m ^{2}$ and wall thickness of $3 cm$. It is filled with ice at $0^{\circ} C$. If the average temperature outside the box is $30^{\circ} C$ throughout the day, the amount of ice that melts in one day is [Use $K_{\text {thermocol }}=0.03 W / mK$ $.L_{\text {fusion (ice) }}=3.00 \times 10^{5} J / kg ]$