List of top Physics Questions asked in WBJEE

An electron of mass ?m? is accelerated by a potential difference V and the corresponding de-Broglie wavelength is $\lambda$. The de Broglie wavelength of a proton of mass M if it is accelerated by the same potential difference is ,
A and B are two parallel sided transparent slabs of refractive indices n$_1 $and n$_2$ respectively. A ray is incident at an angle $\theta$ on the surface of separation of A and B, and after refraction from B into air grazes the surface of B. Then
Two charges of equal amount +Q are placed on a line. Another charge q is placed at the mid-point of the line. The system will be in equilibrium if the value of q is
A micro-ammeter gives full scale deflection at 100 $\mu$A. Its resistance is 2k$\Omega$. The resistance required to convert it to a voltmeter reading 1V is
The increase in electrostatic potential energy of a dipole of moment p when it is taken from parallel to anti-parallel orientation in an electric field E is
A particle of mass ????and carrying a charge ????enters with a velocity ????perpendicular to a uniform magnetic field. The time period of rotation of the particle
If$I_{1}$and$I_{2}$ be the sizes of real images for two positions of a convex lens between object and screen,then the size of the object is
If a bar magnet of magnetic moment M is kept in a uniform magnetic field B, its time period of oscillation is T. In the same magnetic field, the time period of another magnet of same dimension and same mass but of moment M/4 is,
An n-p-n transistor of current gain 80 in common emitter mode gives emitter current equal to 8.1 mA. The base current is
A zener diode has break down voltage of 5.0 V. The resistance required to allow a current of 100 mA through the zener in reverse bias when connected to a battery of emf 12 V is
The magnetic field intensity at the centre of cubical cage of identical wires of length ?a? due to a current I flowing as shown in the fiigure is
A ray of light is incident at an angle $i$ on a glass slab of refractive index $\mu$. The angle between reflected and refracted light is $90^{\circ}$. Then, the relationship between $i$ and $\mu$ is
A large number of particles are placed around the origin, each at a distance $R$ from the origin. The distance of the center of mass of the system from the origin is
The rms speed of oxygen is $v$ at a particular temperature. If the temperature is doubled and oxygen molecules dissociate into oxygen atoms, the rms speed becomes
The length of a metal wire is $L_1$ when the tension is $T_1$ and $L_2$ when the tension is $T_2$. The unstretched length of the wire is
A simple pendulum of length $L$ swings in a vertical plane. The tension of the string when it makes an angle $\theta$ with the vertical and the bob of mass m moves with a speed $v$ is ($g$ is the gravitational acceleration
Two particles $A$ and $B$ are moving as shown in the figure. Their total angular momentum about the point $O$ is
A straight conductor $0.1\, m$ long moves in a uniform magnetic field $0.1\, T$. The velocity of the conductor is $15\, m / s$ and is directed perpendicular to the field. The emf induced between the two ends of the conductor is
Two particles, $A$ and $B$, having equal charges, after being accelerated through the same potential difference enter into a region of uniform magnetic field and the particles describe circular paths of radii $R_{1}$ and $R_{2}$, respectively. The ratio of the masses of $A$ and $B$ is
Particle $A$ moves along $X$-axis with a uniform velocity of magnitude $10\, m / s$. Particle $B$ moves with uniform velocity $20\, m / s$ along a direction making an angle of $60^{\circ}$ with the positive direction of $X$-axis as shown in the figure. The relative velocity of $B$ with respect to that of $A$ is
Block $B$ lying on a table weighs $W$. The coefficient of static friction between the block and the table is $\mu$. Assume that the cord between $B$ and the knot is horizontal. The maximum weight of the block $A$ for which the system will be stationary is
Two copper spheres having same radii, one solid and other hollow, are charged to the same potential. Which of the following statements is correct?
A metal wire of circular cross-section has a resistance $R_1$. The wire is now stretched without breaking so that its length is doubled and the density is assumed to remain the same. If the resistance of the wire now becomes $R_2$ then $R_2 : R_1$ is
A $20\,cm$ long capillary tube is dipped vertically in water and the liquid rises upto $10\, cm$. If the entire system is kept in a freely falling platform, the length of water column in the tube will be
A hollow sphere of external radius $R$ and thickness $t (<< R)$ is made of a metal of density $\rho$, sphere will float in water if