List of top Physics Questions

A collimated beam of laser light of wavelength 514 nm is normally incident on a smooth glass slab placed in air. Given the refractive indices of glass and air are 1.47 and 1.0 respectively, the percentage of light intensity reflected back is:

At a given time \( t \), velocity \( v(t) \) and acceleration \( a(t) \) of a particle undergoing simple harmonic motion are given by
\[ v(t) = -100 \sin \left( 20 t + \frac{\pi}{3} \right), \] \[ a(t) = -2000 \cos \left( 20 t + \frac{\pi}{3} \right). \] Assuming all quantities are in SI units, the amplitude of the oscillation is ............

A compound microscope has its objective with linear magnification of 10. In order to achieve a final magnification of 100, the angular magnification of the eyepiece should be ..........

Consider two particles, each of mass 20 g; the first particle is moving with a speed of 10 m/s along a one-dimensional track in the positive x-direction and collides with the second particle at rest. Assuming that the collision is elastic, the speed (in m/s) of the first particle after the collision is ...............

Consider a spherical particle of mass \( m \) and radius \( r \) moving in a medium. Its velocity at any time is given by \( v = v_0 \exp\left( -\frac{6 \pi X r t}{m} \right) \), where \( v_0 \) is the initial velocity of the particle. The dimensions of \( X \) are

Lenz's law gives

The length of a potentiometer wire is $1200\, cm$ and it carries a current of $60\, mA$. For a cell of emf $5\, V$ and internal resistance of $20 \, \Omega$, the null point on it is found to be at $1000\, cm$. The resistance of whole wire is :

A charge $Q$ is distributed over two concentric conducting thin spherical shells radii $r$ and $R$ $( R > r )$. If the surface charge densities on the two shells are equal, the electric potential at the common centre is :

A particle of charge $q$ and mass $m$ is subjected to an electric field $E = E _{0}\left(1- ax ^{2}\right)$ in the $x$ -direction, where a and $E_{0}$ are constants. Initially the particle was at rest at $x=0$. Other than the initial position the kinetic energy of the particle becomes zero when the distance of the particle from the origin is :

Identify the correct output signal $Y$ in the given combination of gates (as shown) for the given inputs $A$ and $B$.

If the potential energy between two molecules is given by $U = - \frac{ A }{ r ^{6}}+\frac{ B }{ r ^{12}},$ then at equilibrium, separation between molecules, and the potential energy are :

A cube of metal is subjected to a hydrostatic pressure of $4 \,GPa$. The percentage change in the length of the side of the cube is close to (Given bulk modulus of metal, $\left. B =8 \times 10^{10} Pa \right)$

An electrical power line, having a total resistance of $2\Omega,$ delivers $1\, kW$ at $220\, V$. The efficiency of the transmission line is approximately:

Find the torque about the origin when a force of $3 \,\hat{j}\, N$ acts on a particle whose position vector is $2\, \hat {k}\, m$ .

A point charge $q$ of mass $m$ is suspended vertically by a string of length $1$. A point dipole of dipole moment $\vec{ p }$ is now brought towards $q$ from infinity so that the charge moves away. The final equilibrium position of the system including the direction of the dipole, the angles and distances is shown in the figure below. If the work done in bringing the dipole to this position is $N \times( mgh )$, where $g$ is the acceleration due to gravity, then the value of $N$ is_______ .
(Note that for three coplanar forces keeping a point mass in equilibrium, $\frac{F}{\sin \theta}$ is the same for all forces, where $F$ is any one of the forces and $\theta$ is the angle between the other two forces)

A hot filament liberates an electron with zero initial velocity. The anode potential is $1200\,V$. The speed of the electron when it strikes the anode is

By using Kirchoff loop law find the value of 'x' in given circuit.

The inductors of two LR circuits are placed next to each other, as shown in the figure. The values of the self-inductance of the inductors, resistances, mutual-inductance and applied voltages are specified in the given circuit. After both the switches are closed simultaneously, the total work done by the batteries against the induced EMF in the inductors by the time the currents reach their steady state values is _______$mJ$

A light beam of intensity $20\, W/cm^2$ is incident normally on a perfectly reflecting surface of sides $25 \,cm \times 15 \,cm$. The momentum imparted to the surface by the light per second is

The coordinates of centre of mass of a uniform flag shaped lamina (thin flat plate) of mass $4\, kg$. (The coordinates of the same are shown in figure) are :

Consider two ideal diatomic gases $A$ and $B$ at some temperature $T$. Molecules of the gas A are rigid , and have an mass $m$. Molecules of the gas $B$ have an additional vibrational mode, and have a mass $\frac{m}{4}.$ The ratio of the specific heats $(C^{A}_{V}$ and $C^{B}_{V})$ of gas $A$ and $B$, respectively is :

Taking into account of the significant figures, what is the value of $9.99 \,m - 0.0099 \,m$ ?

An ideal fluid flows (laminar flow) through a pipe of non-uniform diameter. The maximum and minimum diameters of the pipes are $6.4\, cm$ and $4.8\, cm$, respectively. The ratio of the minimum and the maximum velocities of fluid in this pipe is :

A vessel of depth $2\,h$ is half filled with a liquid of refractive index $2\sqrt{2}$ and the upper half with another liquid of refractive index $\sqrt{2}$ The liquids are immiscible. The apparent depth of the inner surface of the bottom of vessel will be :

Consider a sphere of radius $R$ which carries a uniform charge density $\rho$. If a sphere of radius $\frac{R}{2}$ Ls carved out of it, as shown, the ratio $\frac{\left|\overrightarrow{E_{A}}\right|}{\left|\overrightarrow{E_{B}}\right|}$ of magnitude of electric field $\overrightarrow{E_{A}}$ and $\overrightarrow{E}_{B}$ respectively, at points A and B due to the remaining portion is :