List of top Physics Questions asked in JEE Main

The number density of molecules of a gas depends on their distance r from the origin as, $n(r) = n_0e^{-\alpha r^4}$ Then the total number of molecules is proportional to :

The output of the given logic circuit is :

The variation of refractive index of a crown glass thin prism with wavelength of the incident light is shown. Which of the following graphs is the correct one, if $D_m$ is the angle of minimum deviation?

There are two long co-axial solenoids of same length $l$. the inner and outer coils have radii $r_1$ and $r_2$ and number of turns per unit length $n_1$ and $n_2$ respectively. The rate of mutual inductance to the self-inductance of the inner-coil is :

Three blocks $A, B$ and $C$ are lying on a smooth horizontal surface, as shown in the figure. $A$ and $B$ have equal masses, $m$ while $C$ has mass $M$. Block $A$ is given an brutal speed $v$ towards $B$ due to which it collides with $B$ perfectly inelastically. The combined mass collides with $C$, also perfectly inelastically $\frac{5}{6}$ th of the initial kinetic energy is lost in whole process. What is value of $M/m$ ?

Three Carnot engines operate in series between a heat source at a temperature $T_1$ and a heat sink at temperature $T_4$ (see figure). There are two other reservoirs at temperature $T_2$, and $T_3$, as shown, with $T_2 > T_2 > T_3 > T_4$ . The three engines are equally efficient if:

Three particles of masses $50\, g, 100\, g$ and $150\, g$ are placed at the vertices of an equilateral triangle of side $1\, m$ (as shown in the figure). The $(x, y)$ coordinates of the centre of mass will be :

Two blocks $A$ and $B$ of masses $m_A = 1 \; kg$ and $m_B = 3 \; kg$ are kept on the table as shown in figure. The coefficient of friction between $A$ and $B$ is $0.2$ and between $B$ and the surface of the table is also $0.2.$ The maximum force $F$ that can be applied on $B$ horizontally, so that the block $A$ does not slide over the block $B$ is : (Take $g = 10 \; m/s^2$)

Two coherent sources produce waves of different intensities which interfere. After interference, the ratio of the maximum intensity to the minimum intensity is $16$. The intensity of the waves are in the ratio:

Two equal resistance when connected in series to a battery, consume electric power of $60\, W$. If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be :

Two guns $A$ and $B$ can fire bullets at speeds $1\, km/s$ and $2\, km/s$ respectively. From a point on a horizontal ground, they are fired in all possible directions. The ratio of maximum areas covered by the bullets fired by the two guns, on the ground is :

Two plane mirrors arc inclined to each other such that a ray of light incident on the first mirror $(M_1)$ and parallel to the second mirror $(M_2)$ is finally reflected from the second mirror $(M_2)$ parallel to the first mirror $(M_1)$. The angle between the two mirrors will be :

The eye can be regarded as a single refracting surface . The radius of curvature of this surface is equal to that of cornea ($7.8\, mm$ ). This surface separates two media of refractive indices 1 and $1.34$. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus.

The graph shows how the magnification $m$ produced by a thin lens varies with image distance $v$. What is the focal length of the lens used ?

The magnetic field of a plane electromagnetic wave is given by $\vec{B} = B_0 \hat{i} [cos (kz - \omega t)] + B_1 \hat{j} cps (kz + \omega t).$ where B$_0 = 3 � 10^{-5} T$ and B$_1 = 2 � 10^{-6}$ T. The rms value of the force experienced by a stationary charge Q = 10 C at z = 0 is closest to :

The magnetic moment of an octahedral homoleptic Mn(II) complex is $5.9\, BM$. The suitable ligand for this complex is :

The resistance of the meter bridge $AB$ is given figure is $4\Omega$ . With a cell of emf $\varepsilon = 0.5 \;V $ and rheostat resistance $R_h = 2 \; \Omega$ the null point is obtained at some point $J$. When the cell is replaced by another one of emf $\varepsilon = \varepsilon_2$ the same null point $J$ is found for $R_h = 6 \; \Omega$. The emf $\varepsilon_2$ is;

The self induced emf of a coil is $25$ volts. When the current in it is changed at uniform rate from $10\, A$ to $25\, A$ in $1s$, the change in the energy of the inductance is :

The top of a water tank is open to air and its water level is maintained. It is giving out $0.74\, m^3$ water per minute through a circular opening of $2\, cm$ radius in its wall. The depth of the centre of the opening from the level of water in the tank is close to :

In a hydrogen like atom, when an electron jumps from the $M$ - shell to the $L$ - shell, the wavelength of emitted radiation is $\lambda$. If an electron jumps from $N$-shell to the $L$-shell, the wavelength of emitted radiation will be :

Two masses $m$ and $\frac{m}{2}$ are connected at the two ends of a massless rigid rod of length $l$. The rod is suspended by a thin wire of torsional constant $k$ at the centre of mass of the rod-mass system(see figure). Because of torsional constant $k$, the restoring torque is $\tau =k\theta$ for angular displacement $\theta$. If the rod is rota ted by $\theta_0$ and released, the tension in it when it passes through its mean position will be:

An $EM$ wave from air enters a medium. The electric fields are $\vec{E_1} = E_{01} \hat{x} \cos \left[ 2 \pi v\left( \frac{z}{c} - t \right) \right]$ in air and $\vec{E}_2 = E_{02} \hat{x} \cos [k (2 z - ct)]$ in medium, where the wave number $k$ and frequency $?$ refer to their values in air. The medium is non-magnetic . If $\in_{r_1} $ and $\in_{r_2} $ refer to relative permittivities of air and medium respectively, which of the following options is correct ?

A plane electromagnetic wave of wavelength $\lambda$ has an intensity I. It is propagating along the positive Y-direction. The allowed expressions for the electric and magnetic fields are given by :

A plane polarized light is incident on a polariser with its pass axis making angle $?$ with $x$-axis, as shown in the figure. At four different values of $\theta, \theta = 8^{\circ}, 38^{\circ} , 188^{\circ} $ and $218^{\circ}$, the observed intensities are same. What is the angle between the direction of polarization and x-axis ?

A plane polarized monochromatic $EM $ wave is traveling in vacuum along $z$ direction such that at $t = t_1$ it is found that the electric field is zero at a spatial point $z_1$. The next zero that occurs in its neighbourhood is at $z_2$. The frequency of the electromagnetic wave is :