List of top Physics Questions

If the relaxation time is doubled and the applied electric field is tripled, then the drift speed of electrons:

A particle of mass 4 mg is executing simple harmonic motion along x-axis with an angular frequency of 40 rad/s. If the potential energy of the particle is $ V(x) = a + bx^2 $, where $ V(x) $ is in joule and $ x $ is in meter, then the value of $ b $ is:

An incompressible fluid is flowing through a tube of uniform cross-section. The increase in the power of the pump required to double the rate of flow is:

Regarding fundamental forces in nature, the correct statement is

The temperature at which the rms speed of oxygen molecules is 75\% of the rms speed of nitrogen molecules at a temperature of $ 287^\circ C $ is:

Wave picture of light has failed to explain
(1) photoelectric effect
(2) interference of light
(3) diffraction of light
(4) polarization of light

The total internal energy of 4 moles of a diatomic gas at a temperature of $27^\circ C$ is: (Universal gas constant $ R = 8.31 \, \text{J mol}^{-1} \text{K}^{-1} $)

A body of mass 'm' tied to one end of a string is whirled in a vertical circle of radius 'R' with zero tension in the string at its highest point. The angle made by the string with the vertical when the kinetic energy of the body becomes half of its maximum kinetic energy is:

A voltmeter of resistance $400 \, \Omega$ is used to measure the emf of a cell with an internal resistance of $4 \, \Omega$. The error in the measurement of emf of the cell is:

If the excess pressures inside two soap bubbles are in the ratio $ 2:3 $, then the ratio of the volumes of the soap bubbles is:

If $ dQ, dU, dW $ are heat energy absorbed, change in internal energy, and external work done respectively by a diatomic gas at constant pressure, then $ dW : dU : dQ $ is:

Four bodies of masses 8 kg, 2 kg, 4 kg and 2 kg are placed at the four corners A, B, C and D respectively of a square ABCD of diagonal 80 cm. The distance of the center of mass of the system from the corner A is:

A constant force of \[ \mathbf{F} = (8\hat{i} - 2\hat{j} + 6\hat{k}) \text{ N} \] acts on a body of mass 2 kg, displacing it from \[ \mathbf{r_1} = (2\hat{i} + 3\hat{j} - 4\hat{k}) \text{ m to } \mathbf{r_2} = (4\hat{i} - 3\hat{j} + 6\hat{k}) \text{ m}. \] The work done in the process is:

The power gain of a transistor operating in common emitter configuration is 32,000. If the input and output resistances of the circuit are 1200 $ \Omega $ and 6000 $ \Omega $ respectively, then the current gain is:

A metal block of mass 120 g is heated to a temperature of 100$^\circ$C and placed on a huge block of ice at 0$^\circ$C. The specific heat capacity of the metal is 0.12 cal/$^\circ$C and the latent heat of fusion of ice is 80 cal/g. The mass of the ice melted is:

A body is thrown vertically upwards with a velocity of 35 ms−1 from the ground.The ratio of the speeds of the body at times 3 s and 4 s of its motion is:

Two particles of charges in the ratio $ 1:2 $ and masses in the ratio $ 2:3 $ moving along a straight line enter a uniform magnetic field at right angles to the direction of the field. If the radii of the circular paths of the particles in the magnetic field are in the ratio $ 3:4 $, then the ratio of the initial linear momenta of the two particles is:

If two electromagnetic waves with electric fields given by $$ \vec{E_1} = E_0 \sin (kx - \omega t) \hat{j} $$ and $$ \vec{E_2} = E_0 \sin (kx - \omega t + \pi) \hat{j} $$ - interfere, then the peak value of the electric field of the resultant wave is

The operation of a nuclear reactor is said to be critical when the value of neutron multiplication factor $ K $ is

A body moving with uniform acceleration travels a distance of 25 m in the fourth second and 37 m in the sixth second. The distance covered by the body in the next two seconds is

The electric flux due to an electric field \[ \vec{E} = (8\hat{i} + 13\hat{j}) \text{ NC}^{-1} \] through an area 3 m$^2$ lying in the XZ plane is:

Two capacitors of capacitances $ 1\mu F $ and $ 2\mu F $ can separately withstand potentials of $ 6 $ kV and $ 4 $ kV respectively. The total potential, they together can withstand when they are connected in series is:

A big liquid drop splits into 'n' similar small drops under isothermal conditions, then in this process:

A block of mass 0.5 kg is at rest on a horizontal table. The coefficient of kinetic friction between the table and the block is 0.2. If a horizontal force of 5 N is applied on the block, the kinetic energy of the block in a time of 4 s is (Acceleration due to gravity = 10 m/s$^2$)

A copper wire of cross-sectional area 0.01 cm$^2$ is subjected to a tension of 22 N. If Young’s modulus and Poisson’s ratio of copper are $1.1 \times 10^{11}$ Nm$^2$ and 0.32 respectively, then the change in the cross-sectional area of the wire is: