List of top Physics Questions asked in WBJEE

Consider two concentric spherical metal shells of radii $r_1$ and $r_2 (r_2 > r_1)$. If the outer shell has a charge $q$ and the inner one is grounded, the charge on the inner shell is
An infinite sheet carrying a uniform surface charge density o lies on the $x y$-plane. The work done to carry a charge $q$ from the point $A =a(\hat{ i }+2 \hat{ j }+3 \hat{ k })$ to the point $B =a(\hat{ i }-2 \hat{ j }+6 \hat{ k })$ (where $a$ is a constant with the dimension of length and $\varepsilon_{0}$ is the permittivity of free space) is
To determine the coefficient of friction between a rough surface and a block, the surface is kept inclined at $45^{\circ}$ and the block is released from rest. The block takes a time $t$ in moving a distance $d$. The rough surface is then replaced by a smooth surface and the same experiment is repeated. The block now takes a time $t / 2$ in moving down the same distance $d$. The coefficient of friction is
Three capacitors $3\, \mu F , 6 \, \mu F$ and $6\, \mu F$ are connected in series to a source of $120 \, V$. The potential difference, in volt, across the $3 \, \mu F$ capacitor will be
A solid uniform sphere resting on a rough horizontal plane is given a horizontal impulse directed through its center so that it starts sliding with an initial velocity $v_0$. When it finally starts rolling without slipping the speed of its center is
The energy of gamma $(?)$ ray photon is $E_?$ and that of an X-ray photon is $E_x$. If the visible light photon has an energy of $E_v$ , then we can say that
A particle moves with constant acceleration along a straight line starting from rest. The percentage increase in its displacement during the $4^{th}$ second compared to that in the $3^{rd}$ second is
A uniform solid spherical ball is rolling down a smooth inclined plane from a height $h$. The velocity attained by the ball when it reaches the bottom of the inclined plane is $v$. If the ball is now thrown vertically upwards with the same velocity $v$, the maximum height to which the ball will rise is
A $10\, W$ electric heater is used to heat $a$ container filled with $0.5\, kg$ of water. It is found that the temperature of water and the container rises by $3^{\circ}\, K$ in $15 \,min .$ The container is then emptied, dried and filled with $2 \,kg$ of oil. The same heater now raises the temperature of container-oil system by $2^{\circ} \,K$ in $20 \,min$. Assuming that there is no heat loss in the process and the specific heat of water is $4200\, J\, kg ^{-1} \,K ^{-1}$, the specific heat of oil in the same unit is equal to
A whistle whose air column is open at both ends has a fundamental frequency of $5100 \,Hz$. If the speed of sound in air is $340\, ms^{-1}$, the length of the whistle, in cm, is
A long conducting wire carrying a current $I$ is bent at $120^{\circ}$ (see figure). The magnetic field $B$ at a point $P$ on the right bisector of bending angle at a distance d from the bend is $\left(\mu_{0}\right.$ is the permeability of free space)
One mole of an ideal monoatomic gas is heated at a constant pressure from $0^{\circ} C$ to $100^{\circ} C$. Then the change in the internal energy of the gas is (Given $R=8.32 \,J\,mol ^{-1} \,K ^{-1}$ )
A circuit consists of three batteries of emf $E_{1}=1 \,V , E_{2}=2 \,V$ and $E_{3}=3 \,V$ and internal resistances $1 \,\Omega, 2\, \Omega$ and $1\, \Omega$ respectively which are connected in parallel as shown in the figure . The potential difference between points $P$ and $Q$ is 
A small metal sphere of radius $a$ is falling with a velocity $v$ through a vertical column of a viscous liquid. If the coefficient of viscosity of the liquid is $\eta$ then the sphere encounters an opposing force of
To determine the composition of a bimetallic alloy, a sample is first weighed in air and then in water. These weights are found to be $w_1$ and $w_2$ respectively. If the densities of the two constituent metals are $\rho_1$ and $\rho_2$ respectively, then the weight of the first metal in the sample is (where $\rho_w$ is the density of water)
A glass slab consists of thin uniform layers of progressively decreasing refractive indices $RI$ (see figure) such that the $RI$ of any layer is $\mu-m\Delta \mu$. Here $\mu$ and $\Delta \mu$ denote the $RI$ of $0^{th}$ layer and the difference in $RI$ between any two consecutive layers, respectively. The integer $m = 0, 1, 2, 3.....$ denotes the numbers of the successive layers. A ray of light from the 0th layer enters the $1^{st}$ layer at an angle of incidence of $30^\circ$. After undergoing the $m^{th}$ refraction, the ray emerges parallel to the interface. If $\mu = 1.5$ and $\Delta \mu = 0.015$, the value of $m$ is
The intermediate image formed by the objective of a compound microscope is
A sphere of radius R has a volume density of charge $? = kr$, where r is the distance from the centre of the sphere and k is constant. The magnitude of the electric field which exists at the sur ace o the sphere is given by ($e_0$ = permittivity of the free space)
A bar magnet has a magnetic moment of $200\, A \,m^2$. The magnet is suspended in a magnetic field of $0.30\, N\, A^{-1}\, m^{-1}$. The torque required to rotate the magnet from its equilibrium position through an angle of $30^{\circ}$, will be
A bullet of mass $m$ travelling with a speed $v$ hits a block of mass $M$ initially at rest and gets embedded in it. The combined system is free to move and there is no other force acting on the system. The heat generated in the process will be
A travelling acoustic wave of frequency $500\, Hz$ is moving along the positive $x$-direction with a velocity of $300 \,ms^{-1}$. The phase difference between two points $x_1$ and $x_2$ is 60$^{\circ}$. Then the minimum separation between the two pints is
Four small objects each of mass m are fixed at the corners of a rectangular wire-frame of negligible mass and of sides $a$ and $b (a > b)$. If the wire frame is now rotated about an axis passing along the side of length b, then the moment of inertia of the system for this axis of rotation is
An equilateral triangle is made by uniform wires $AB, BC, CA. A$ current $I$ enters at $A$ and leaves from the mid point of $BC$. If the lengths of each side of the triangle is $L$, the magnetic field $B$ at the centroid $O$ of the triangle is
An electron of charge $e$ and mass $m$ is moving in circular path of radius $r$ with a uniform angular speed $\omega$. Then which of the following statements are correct ?
An alpha particle (He)has a mass of 4.00300 amu. A proton has mass of 1.00783 amu and a neutron has mass of 1.00867 amu respectively. The binding energy of alpha particle estimated from these data is the closest to