List of top Physics Questions asked in WBJEE

The de-Broglie wavelength of a moving bus with speed \( v \) is \( \lambda \). Some passengers left the bus at a stop. Now, when the bus moves with twice of its initial speed, its kinetic energy is found to be twice of its initial value. What is the de-Broglie wavelength of the bus now?
One end of a steel wire is fixed to the ceiling of an elevator moving up with an acceleration \( 2 \, \text{m/s}^2 \) and a load of 10 kg hangs from the other end. If the cross-section of the wire is \( 2 \, \text{cm}^2 \), then the longitudinal strain in the wire will be (Take \( g = 10 \, \text{m/s}^2 \) and \( Y = 2.0 \times 10^{11} \, \text{N/m}^2 \)).
Oneendofasteelwireisfixedtotheceiling
Six vectors \( \mathbf{a}, \mathbf{b}, \mathbf{c}, \mathbf{d}, \mathbf{e}, \mathbf{f} \) have the magnitudes and directions indicated in the figure. Which of the following statements is true?
What are the charges stored in the 1 µF and 2 µF capacitors in the circuit as shown in the figure once the current (\( I \)) becomes steady?
Figure shows the graph of angle of deviation \( \delta \) versus angle of incidence \( i \) for a light ray striking a prism. The prism angle is
angle of deviation δ versus angle of incidence i
If the dimensions of length are expressed as \( G^x C^y h^z \), where \( G \), \( C \), and \( h \) are the universal gravitational constant, speed of light, and Planck's constant respectively, then:
A wave disturbance in a medium is described by \[ y(x,t) = 0.02 \cos\left(50 \pi t + \frac{\pi}{2}\right) \cos(10 \pi x) \] where \( x \) and \( y \) are in meters and \( t \) is in seconds. Which statement(s) is/are correct?
Let \( \bar{V} \), \( V_{\text{rms}} \), \( V_p \) denote the mean speed, root mean square speed, and most probable speed of the molecules of mass \( m \) in an ideal monoatomic gas at absolute temperature \( T \) Kelvin. Which statement(s) is/are correct?
Let the binding energy per nucleon of a nucleus be denoted by \( E_{\text{b/n}} \), and the radius of the nucleus is denoted by \( r \). If the mass numbers of nuclei A and B are 64 and 125 respectively, then:
\( 10^{20} \) photons of wavelength 660 nm are emitted per second from a lamp. The wattage of the lamp is: \[ \text{(Planck's constant} \, h = 6.6 \times 10^{-34} \, \text{Js}) \]
A piece of granite floats at the interface of mercury and water contained in a beaker as shown in the figure. If the densities of granite, water, and mercury are \( \rho \), \( \rho_1 \), and \( \rho_2 \) respectively, the ratio of the volume of granite in water to the volume of granite in mercury is:
A piece of granite floats at the interface of mercury and water
The equation of a stationary wave along a stretched string is given by \[ y = 5 \sin \left( \frac{\pi x}{3} \right) \cos (40 \pi t) \] Additional Information Here, \(x\) and \(y\) are in cm and \(t\) in seconds. The separation between two adjacent nodes is:
Temperature of a body \( \theta \) is slightly more than the temperature of the surrounding \( \theta_s \). Its rate of cooling (R) versus temperature of the body (\( \theta \)) is plotted. Its shape would be:
The variation of the density of a solid cylindrical rod of cross-sectional area \( \alpha \) and length \( L \) is given by: \[ \rho(x) = \rho_0 \frac{x^2}{L^2} \] Where \( x \) is the distance from one end of the rod. The position of its center of mass from one end is:
Consider a particle of mass 1 gm and charge 1.0 Coulomb at rest. Now, the particle is subjected to an electric field \( E(t) = E_0 \sin(\omega t) \) in the x-direction, where \( E_0 = 2 \, \text{N/C} \) and \( \omega = 1000 \, \text{rad/sec} \). The maximum speed attained by the particle is:
A radioactive nucleus decays as follows: \[ X \to X_1 \to X_2 \to X_3 \to X_4 \] If the mass number and atomic number of \( X_4 \) are 172 and 69 respectively, the mass number and atomic number of \( X \) are:
Three different liquids are filled in a U-tube as shown in the figure. Their densities are \( \rho_1 \), \( \rho_2 \), and \( \rho_3 \), respectively. From the figure, we may conclude that:
Three different liquids are filled in a U-tube
A single slit diffraction pattern is obtained using a beam of red light. If red light is replaced by blue light, then:
Which logic gate is represented by the following combination of logic gates?
logic gate is represented by the following combination of logic gates
A force \( \mathbf{F} = ai + bj + ck \) is acting on a body of mass \( m \). The body was initially at rest at the origin. The co-ordinates of the body after time \( t \) will be:
The variation of displacement with time of a simple harmonic motion (SHM) for a particle of mass \( m \) is represented by: \[ y = 2 \sin \left( \frac{\pi}{2} + \phi \right) \, \text{cm} \] The maximum acceleration of the particle is:
A diode is connected in parallel with a resistance as shown in Figure. The most probable current (\( I \)) - voltage (\( V \)) characteristic is:
A ball falls from a height \( h \) upon a fixed horizontal floor. The coefficient of restitution between the ball and the floor is \( e \). The total distance covered by the ball before it comes to rest is:
Acceleration-time (\( a \) vs. \( t \)) graph of a body is shown in the figure. Corresponding velocity-time (\( v \) vs. \( t \)) graph is:
The minimum force required to start pushing a body up a rough (having coefficient of friction \( \mu \)) inclined plane is \( F_1 \), while the minimum force needed to prevent it from sliding is \( F_2 \). If the inclined plane makes an angle \( \theta \) with the horizontal such that \( \tan\theta = 2\mu \), then the ratio \( \frac{F_1}{F_2} \) is: