List of top Physics Questions

A train of $150 \, m$ length is going towards north direction at a speed of $10 \, ms^{-1}$. A parrot flying at the speed of $5 \, ms^{-1}$ towards south direction parallel to the railway track. The time taken by the parrot to cross the train is equal to

A proton, a deuteron and an $\alpha$-particle accelerated through the same potential difference enter a region of uniform magnetic field, moving at right angles to $B$. What is the ratio of their K.E.?

A person walks up a stationary escalator in time $t_1$. If he remains stationary on the escalator, then it can take him up in time $t_2$. How much time would it take him to walk up the moving escalator?

A particle is released from a height $h$. At a certain height, its kinetic energy is two times its potential energy. Height and speed of the particle at that instant are

A flywheel rotates with a uniform angular acceleration. Its angular velocity increases from $20\pi \, { rad\, s^{-1}}$ to $40\pi \, { rad\, s^{-1}}$ in 10 seconds. How many rotations did it make in this period?

The wavefront of a distant source of unknown shape is approximately

The temperature of two bodies $A$ and $B$ are respectively, $727?C$ and $327?C$. The ratio $H_A : H_B$ of the rates of heat radiated by them is

Which one of the following substances has the largest specific heat?

A copper rod of length $l$ is rotated about the end perpendicular to the uniform magnetic field $B$ with constant angular velocity $\omega$. The induced e.m.f. between the two ends is

A circular coil of radius $0.1\, m$ has $80$ turns of wire. If the magnetic field through the coil increases from $0\, to\, 2$ tesla in $0.4 \,s$ and the coil is connected to a $11 \,\Omega$ resistor, what is the current flow through the resistor during the 0.4 s?

Let $v_{rms}, v_{mp}$ and $v_{avg}$ represent the root mean square, the most probable and the average velocities respectively, in case of a gaseous system in equilibrium at certain temperature. Then, $(v_{rms})^2 : (v_{mp})^2 : (v_{avg})^2$ is

Two identical circular coils $A$ and $B$ are kept on a horizontal tube side by side without touching each other. If the current in the coil $A$ increases with time, in response, the coil $B$

The width of the depletion region in a p-n junction diode is

A truck accelerates from speed $\upsilon \,to\, 2\upsilon$. Work done in during this is

A radioactive substance emits $100$ beta particles in the first $2$ seconds and $50$ beta particles in the next $2$ seconds. The mean life of the sample is

Radii of curvature of a converging lens are in the ratio $1 : 2$. Its focal length is $6 \,cm$ and refractive index is $1.5$. Then its radii of curvature are

A series combination of resistor $(R)$ and capacitor $(C)$ is connected to an $AC$ source of angular frequency $'\omega'$. Keeping the voltage same, if the frequency is changed to $\frac{\omega}{3}$ , the current becomes half of the original current. Then the ratio of the capacitive reactance and resistance at the former frequency is

The wavelength $\lambda_e$ of an electron and $\lambda_P$ of a photon of same energy E are related by:

When a proton is released from rest in a room, it starts with an initial acceleration $a_0$ towards west. When it is projected towards north with a speed $v_0$ it moves with an initial acceleration $3a_0$ towards west. The electric and magnetic fields in the room are:

Infinite number of bodies, each of mass 2 kg are situated on x-axis at distance 1m, 2m, 4m, 8m, ...., respectively, from the origin. The resulting gravitational potential due to this system at the origin will be

An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass $1\, kg$ moves with a speed of $12 \, ms^{-1}$ and the second part of mass $2 \,kg$ moves with $8 \, ms^{-1}$ speed. If the third part files off with $4 \, ms^{-1}$ speed, then its mass is :

The heart is pumping blood at x kg per unit time, with a constant velocity v. The force required is

The transverse displacement of a string fixed at both ends is given by $y=0.6 \sin \left(\frac{2 \pi x}{3}\right) \cos (120 \pi t)$ where $x$ and $y$ are in metres and $t$ is in seconds. The length of the string is $1.5\, m$ and its mass is $3.0 \times 10^{-2} kg$. The tension in the string is equal to

In the Wheatstone's network given, \(P = 10\,\Omega , Q = 20\,\Omega , R = 15 \,\Omega , S = 30 \,\Omega\), the current passing through the battery (of negligible internal resistance) is

A solid body of constant heat capacity $1 \,J/?C$ is being heated by keeping it in contact with reservoirs in two ways : (i) Sequentially keeping in contact with $2$ reservoirs such that each reservoir supplies same amount of heat. (ii) Sequentially keeping in contact with $8$ reservoirs such that each reservoir supplies same amount of heat. In both the cases body is brought from initial temperature $100^{\circ}C$ to final temperature $200^{\circ}C$. Entropy change of the body in the two cases respectively is :