List of top Physics Questions asked in WBJEE

\(\theta\) elimination from the equations \[ x^{2}+y^{2}=\frac{x\cos3\theta+y\sin3\theta}{\cos^{3}\theta} =\frac{y\cos3\theta-x\sin3\theta}{\sin^{3}\theta} \] will be:
If \(\alpha, \beta\) are the roots of the equation \(x^{2}-px+q=0\) and \(\alpha>0\), \(\beta>0\), then \[ \alpha^{\frac{1}{4}}+\beta^{\frac{1}{4}}=(p+6\sqrt{q}+4q^{\frac{1}{4}}\sqrt{p+2\sqrt{q}})^{\kappa}, \] where \(\kappa\) is:
Consider the function \(y=f(x)\) defined implicitly by the equation \[ y^{3}-3y+x=0 \] on the interval \((-\infty,-2)\cup(2,\infty)\). The area of the region bounded by the curve \(y=f(x)\), the x-axis and the lines \(x=a,x=b\), where \(-\infty<a<b<-2\) is:
Which of the following plot(s) is/are correct representation(s) of Boyle's Law?
The mass of an electron is \(9.1\times10^{-31}\ \text{kg}\). If its K.E. is \(3.0\times10^{-25}\ \text{J}\), its wavelength is (approximately):
Three engines A, B and C take steam at \( 130^\circ\text{C} \) and reject it at \( 20^\circ\text{C} \), \( 40^\circ\text{C} \) and \( 50^\circ\text{C} \) respectively. The most efficient engine will be
For Boolean variables A and B, \( A \oplus B = A\bar{B} + \bar{A}B \). Then, which of the following statements is/are correct?
Two points of monochromatic and coherent sources of light of wavelength \( \lambda \) each, are placed as shown in figure. The initial phase difference between the sources is zero, (\( D \gg d \)). Mark the correct statement(s).

The displacement current flows through a capacitor when the voltage across its plates
The moment of inertia of a thin disc about axes \( a, b, c, d \) are \( I_1, I_2, I_3 \) and \( I_4 \) respectively, as shown in figure. If the moment of inertia about an axis passing through the centre and perpendicular to the plane of the disc is I then,

Which of the velocity-time \( (v-t) \) graph(s) can possibly represent one-dimensional motion of a particle?
2 moles of an ideal gas with \( \frac{C_p}{C_v} = \frac{5}{3} \) are mixed with 3 moles of another ideal gas with \( \frac{C_p}{C_v} = \frac{4}{3} \). The value of \( \frac{C_p}{C_v} \) for the mixture is
The circuit has two oppositely connected ideal diodes in parallel as shown in the figure. What is the current flowing in the circuit?

An electromagnetic wave, whose wave normal makes an angle of \( 45^\circ \) with the vertical, is travelling in air and strikes a horizontal liquid surface. While travelling through the liquid, it gets deviated by \( 15^\circ \). If the speed of electromagnetic wave in air is \( 3\times10^8 \text{ m/s} \), then the speed of electromagnetic wave in the liquid will be
The de-Broglie wavelength of an electron in 4th orbit is (where \( r \) = radius of the 1st orbit)
A particle of mass \( m \) is suspended from a point O by a string of length \( R \). It is given a velocity \( u = 3\sqrt{gR} \) at the bottom. The difference in tension at point B and at the point C is


A pipe A is connected with other pipes B and C as shown in the figure. The areas of cross-section of A, B and C are respectively \( \alpha \), \( \frac{\alpha}{2} \) and \( \frac{\alpha}{4} \). If the velocities of flow of water through A and B are 10 m/sec and 6 m/sec, respectively, then velocity of flow, \( V_c \) along C is

A uniform rod AB is suspended from a point P, at a variable distance x, from A, as shown in figure. To make the rod horizontal, a mass 'm' is suspended from its end A. Which set of variables will give a straight line when they are plotted?

The magnetic moment of an iron bar is \( M \). It is now bent in such a way that it forms an arc section of a circle subtending an angle of \( 60^\circ \) at the centre. The magnetic moment of the arc section is
A radioactive element \( {}^{242}_{92}\text{X} \) emits two \( \alpha \)-particles, one electron and two positrons. The transformed nucleus is represented by \( {}^{234}_{P}\text{Y} \). The value of \( P \) is
Two spherical soap bubbles of radii \( r_1 \) and \( r_2 \) in vacuum coalesce under isothermal condition. The newly formed bubble has a radius (\( r \)) given by
Radiation of wavelength \( \lambda \) is incident on a photocell. The fastest emitted electron has speed \( v \). If the wavelength is changed to \( \frac{3\lambda}{4} \), then the speed of the fastest emitted electron will be
A ray of light travelling in air is incident on one face of a parallel glass slab of thickness \( t \) and refractive index \( \mu \) at an angle of incidence \( i \). Total time spent by the ray inside the slab is
Which one of the following graphs represents the velocity-time (v - t) graph of a small spherical body falling in a viscous liquid?
Three blocks of masses \( m_1 = 2\text{ kg} \), \( m_2 = 3\text{ kg} \) and \( m_3 = 5\text{ kg} \) are placed on a horizontal frictionless surface and a force of \( 30\text{ N} \) pulls the system as shown below. The value of tension \( T \) will be