List of top Physics Questions

The velocity of a particle is given by the equation $ v(x) = 3x^2 - 4x $, where $ x $ is the distance covered by the particle. The expression for its acceleration is:

A battery of emf $ 8V $ and internal resistance $ 0.5 \Omega $ is being charged by a $ 120V $ DC supply using a series resistor of $ 15.5 \Omega $. The terminal voltage of the $ 8V $ battery during charging is:

The acceleration of a particle which moves along the positive $ x $-axis varies with its position as shown in the figure. If the velocity of the particle is $ 0.8 \, {m/s} $ at $ x = 0 $, then its velocity at $ x = 1.4 \, {m} $ is: \includegraphics[]{83.png}

Two objects of masses 2 kg and 5 kg possess velocities $ 10 \hat{i} \, {m/s} $ and $ 3 \hat{i} + 5 \hat{j} \, {m/s} $ respectively. Then the velocity of C.M. in m/s is:

An electron is moving with a velocity $ (2\hat{i} + 3\hat{j}) $ m/s in an electric field $ (3\hat{i} + 6\hat{j} + 2\hat{k}) $ V/m and a magnetic field $ (2\hat{j} + 3\hat{k}) $ T. The magnitude and direction (with x-axis) of the Lorentz force acting on the electron is

In the Young's double slit experiment, the 2nd bright fringe for red light coincides with the 3rd bright fringe for violet light. Then the value of 'n' is: (Given: wavelength of red light = 6300 $\text{Å}$ and wavelength of violet light = 4200 $\text{Å}$)

E, m, L, G represent energy, mass, angular momentum and gravitational constant respectively. The dimensions of \[ \frac{EL^2}{mG^2} \] will be that of

A projectile can have the same range $ R $ for two angles of projection. Their initial velocities are the same. If $ T_1 $ and $ T_2 $ are times of flight in two cases, then the product of two times of flight is directly proportional to:

If \[ | \vec{P} + \vec{Q} | = | \vec{P} | = | \vec{Q} |, \] then the angle between $ \vec{P} $ and $ \vec{Q} $ is:

When an electron placed in a uniform magnetic field is accelerated from rest through a potential difference $ V_1 $, it experiences a force $ F $. If the potential difference is changed to $ V_2 $, the force experienced by the electron in the same magnetic field is $ 2F $, then the ratio of potential differences $ \frac{V_2}{V_1} $ is:

A 4 kg stone is attached to a steel wire being whirled at a constant speed of $ 12 $ m/s in a horizontal circle. The wire is 4 m long with a diameter of 2 mm, and Young’s modulus is $ 2 \times 10^{11} $ Nm$^2$. The strain in the wire is:

A spherical ball of radius $ 1 \times 10^{-4} $ m and density $ 10^4 $ kgm$^{-3}$ falls freely under gravity before entering water. The distance $ h $ before velocity change in water is:

An ideal gas is found to obey $ PV^{\frac{3}{2}} = \text{constant} $ during an adiabatic process. If such a gas initially at a temperature $ T $ is adiabatically compressed to $ \frac{1}{4} $th of its volume, then its final temperature is:

The condition $ dw = dq $ holds good in the following process:

The efficiency of a Carnot engine is found to increase from 25\% to 40\% on increasing the temperature ($T_1$) of the source alone through 100 K. The temperature ($T_2$) of the sink is given by:

The electric field intensity ($E$) at a distance of 3 m from a uniform long straight wire of linear charge density 0.2 $\mu C m^{-1}$ is:

A cell of emf 1.2 V and internal resistance 2 $ \Omega $ is connected in parallel to another cell of emf 1.5 V and internal resistance 1 $ \Omega $. If the like poles of the cells are connected together, the emf of the combination of the two cells is:

A proton and an alpha particle moving with energies in the ratio $ 1:4 $ enter a uniform magnetic field of 37 T at right angles to the direction of the field. The ratio of the magnetic forces acting on the proton and the alpha particle is:

A charged particle moving along a straight-line path enters a uniform magnetic field of $ 4 $ mT at right angles to the direction of the magnetic field. If the specific charge of the charged particle is $ 8 \times 10^7 $ C/kg, the angular velocity of the particle in the magnetic field is:

At a place the horizontal component of earth’s magnetic field is $ 3 \times 10^{-5} $ T and the magnetic declination is $ 30^\circ $. A compass needle of magnetic moment $ 18 $ A$m^2$ pointing towards geographic north at this place experiences a torque of:

The RMS value of the electric field of an electromagnetic wave emitted by a source is $ 660 $ N/C. The average energy density of the electromagnetic wave is:

The maximum wavelength of light which causes photoelectric emission from a photosensitive metal surface is $ \lambda_0 $. Two light beams of wavelengths $ \frac{\lambda_0}{3} $ and $ \frac{\lambda_0}{9} $ incident on the metal surface. The ratio of the maximum velocities of the emitted photoelectrons is:

The electrostatic potential energy of the electron in an orbit of hydrogen is $ -6.8 $ eV. The speed of the electron in this orbit is (C is the speed of light in vacuum):

The surface areas of two nuclei are in the ratio $ 9:25 $. The mass numbers of the nuclei are in the ratio:

Pure silicon at 300K has equal electron and hole concentration of $ 1.5 \times 10^{16} $ m$^{-3}$. If the hole concentration increases to $ 3 \times 10^{22} $ m$^{-3}$, then the electron concentration in the silicon is: