List of top Questions asked in WBJEE

If the kinetic energies of an electron, an alpha particle, and a proton having the same de-Broglie wavelength are $\varepsilon_1, \varepsilon_2, \varepsilon_3$ respectively, then
In a Young's double slit experiment, the intensity of light at a point on the screen where the path difference between the interfering waves is $\lambda$ (where $\lambda$ is the wavelength of light used) is $1$. The intensity at a point where the path difference is $\frac{\lambda}{4}$ will be (assume two waves have the same amplitude)
A Zener diode having a breakdown voltage $V_z = 6$ V is used in a voltage regulator circuit as shown in the figure. The minimum current required to pass through the Zener to act as a voltage regulator is $10$ mA and the maximum allowed current through the Zener is $40$ mA. The maximum value of $R_\delta$ for Zener to act as a voltage regulator is
A Zener diode having a breakdown voltage
The expression $A(A + B) + (B + AA)(A + B)$ simplifies to
Suppose in a hypothetical world the angular momentum is quantized to be even integral multiples of $\frac{h}{2}$. The largest possible wavelength emitted by hydrogen atoms in the visible range in a world according to Bohr's model will be (consider $h_e = 1224$ MeV-fm)
Given: The percentage error in the measurements of A, B, C, and D are respectively 4%, 2%, 3%, and 1%. The relative error in $Z = \frac{A^4 B^{1/3}}{C D^{3/2}}$ is
The Entropy ($S$) of a black hole can be written as $S = \beta k_B A$, where $k_B$ is the Boltzmann constant and $A$ is the area of the black hole. Then $\beta$ has dimension of
A straight wire is placed in a magnetic field that varies with distance $x$ from origin as $B = B_0 (2 - \frac{x}{n}) \hat{k}$. The ends of the wire are at $(a, 0)$ and $(2n, 0)$ and it carries a current $I$. If the force on the wire is $F = 1 B_0 \left(\frac{k a}{2}\right) \hat{j}$, then the value of $k$ is
In a closed circuit there is only a coil of inductance $L$ and resistance $100\ \Omega$. The coil is situated in a uniform magnetic field. All of a sudden, the magnetic flux linked with the circuit changes by $5$ Weber. What amount of charge will flow in the circuit as a result?
An electron revolves around the nucleus in a circular path with angular momentum $L$. A uniform magnetic field $B$ is applied perpendicular to the plane of its orbit. If the electron experiences a torque $T$, then
When an AC source of EMF $E$ with frequency = 100 Hz is connected across a circuit, the phase difference between $E$ and current $I$ in the circuit is observed to be $\pi/4$ as shown in the figure. If the circuit consists of only RC or RL in series, then
When an AC source of EMF
A battery of emf E and internal resistance r is connected with an external resistance R as shown in figure. The battery will act as a constant voltage source if:
A battery of emf E and internal resistance r
In Young's double slit experiment with monochromatic light, the maximum intensity is 4 times the minimum intensity in the interference pattern. What is the ratio of the intensities of the two interfering waves?
The human eye has an approximate angular resolution of $\theta = 5.8 \times 10^{-4}$ rad, and a typical photo printer prints a minimum of 300 dpi (dots per inch, $1$ inch = $2.54$ cm). At what minimal distance $d$ should the printed page be held so that one does not see the individual dots?
Two charges, each equal to $-q$, are kept at $(-a, 0)$ and $(a, 0)$. A charge $q$ is placed at the origin. If $q$ is a small displacement along the $y$ direction, the force acting on $q$ is proportional to
Consider a thermodynamic process where internal energy $U \equiv A p^2 V$ (A = Constant). If the process is performed adiabatically, then
A neutral conducting solid sphere of radius $R$ has two spherical cavities of radii $a$ and $b$ as shown in the figure. The center-to-center distance between the two cavities is $c$. $q_a$ and $q_b$ charges are placed at the centers of cavities respectively. The force between $q_a$ and $q_b$ is
A neutral conducting solid sphere of radius
Consider two concentric conducting spheres of radii $R$ and $2R$ respectively. The inner sphere is given a charge $+Q$. The other sphere is grounded. The potential at $r = \frac{3R}{2}$ is
Two infinite line charges parallel to each other are moving with a constant velocity $v$ in the same direction as shown in the figure. The separation between two line charges is $d$. The magnetic attraction balances the electric repulsion when, [e = speed of light in free space]
Two infinite line charges parallel to each other are moving with
The electric potential for an electric field directed parallel to the X-axis is shown in the figure. Choose the correct plot of electric field strength.
A body of mass $m$ is thrown vertically upward with speed $\sqrt{3}v_e^2$, where $v_e$ is the escape velocity of a body from earth surface. The final velocity of the body is
A particle is subjected to two simple harmonic motions in the same direction having equal amplitudes and equal frequency. If the resultant amplitude is equal to the amplitude of the individual motion, the phase difference $(\delta)$ between the two motions is
A body of mass $m$ is thrown with velocity $u$ from the origin of a coordinate axes at an angle with the horizon. The magnitude of the angular momentum of the particle about the origin at time $t$ when it is at the maximum height of the trajectory is proportional to
27 drops of mercury coalesce to form a bigger drop. What is the relative increase in surface energy?
Certain amount of an ideal gas is taken from its initial state 1 to final state 4 through the paths 1 → 2 → 3 → 4 as shown in the figure AB, CD, EF are all isotherms. If $v_p$ is the most probable speed of the molecules, then:
Certain amount of an ideal gas is taken from its initial state 1 to final