List of top Physics Questions asked in KCET, WBJEE

Three identical convex lenses each of focal length f are placed in a straight line separated by a distance f from each other. An object is located in \(\frac{f}{2}\) in front of the leftmost lens. Then,

The Curie temperatures of Cobalt and iron are 1400K and 1000K respectively. At T = 1600K , the ratio of magnetic susceptibility of Cobalt to that of iron is

A particle is in uniform circular motion. Related to one complete revolution of the particle, which among the stataments is incorrect ?

A particle of mass m is projected at velocity at a velocity u, making an angle θ with the horizontal(x-axis). If the angle of projection θ is varied keeping all other parameters same, then magnitude of angular momentum(L) at its maximum height about the point of projection varies with θ as,

The energy gap of an LED is 2.4 eV. When the LED is switched ‘ON’, the momentum of the emitted photons is

An equiconvex lens made of glass of refractive index \(\frac{3}{2}\) has focal length f in air. It is completely immersed in water of refractive index \(\frac{4}{3}\). The percentage change in the focal length is

A metallic rod of length 1 m held along east-west direction is allowed to fall down freely. Given horizontal component of earth’s magnetic field B_H = 3 × 10^-5 T. The emf induced in the rod at an instant t = 2s after it is released is ( Take g = 10 ms^-2 )

The P-V diagram of a Carnot's engine is shown in the graph below. The engine uses 1 mole of an ideal gas as working substance. From the graph, the area enclosed by the P-V diagram is
[ The heat supplied to the gas is 8000 J ]

A point object is moving at a constant speed of 1 ms^-1 along the principal axis of a convex lens of focal length 10cm. The speed of the image is also 1 ms^-1 , when the object is at _______ cm from the optic centre of the lens.

A cubical Gaussian surface has side of length a = 10 cm. Electric field lines are parallel to x-axis as shown. The magnitudes of electric fields through surfaces ABCD and EFGH are 6kNC^-1 and 9kNC^-1 respectively. Then the total charge enclosed by the cube is
[Take ε₀ = 9 × 10^-12 Fm^-1]

In the Young’s double slit experiment, the intensity of light passing through each of the two double slits is 2 × 10^-2 Wm^-2. The screen-slit distance is very large in comparison with slit-slit distance. The fringe width is β. The distance between the central maximum and a point P on the screen is \(\frac{\beta}{3}\). Then the total light intensity at that point is

A stretched wire of a material whose Young's modulus Y = 2 × 10¹¹ Nm^-2 has Poisson's ratio of 0.25. Its lateral strain ε_l = 10^-3. The elastic energy density of the wire is

A full-wave rectifer with diodes D₁ and D₂ is used to rectify 50 Hz alternating voltage. The diode D₁ conducts _______ times in one second.

In an experiment on a circuit, as shown in the figure, the voltmeter shows 8V reading. The resistance of the voltmeter is 

A balloon starting from rest ascends from the ground with a uniform acceleration of 4 ft/sec². At the end of 5 sec, a stone is dropped from it. If t be the time to reach the stone to the ground and H is the height of the balloon when the stone goes to the floor, Then

A train is moving along the tracks at a constant speed u. A girl on the train throws a ball of mass m straight ahead along the direction of motion of the train with speed v with respect to herself. Then,

Consider the logic circuit with inputs A,B,C, and output Y. How many combinations of A, B and C give the output Y=0?

A body of mass 2 kg moves in a horizontal circular path of radius 5m. In an instant its speed is \(2\sqrt5\) m/s and is increasing at the rate of 3 m/s².The magnitude of the force acting on the body at the instant is,

A positively charged glass rod is brought near uncharged metal sphere, which is mounted on an insulated stand. If the glass rod is removed, the net charge on the metal sphere is

The ratio of the magnitudes of electric field to the magnetic field of an electromagnetic wave is of the order of

For a given electric current the drift velocity of conduction electrons in a copper wire is v_d and their mobility is μ . When the current is increased at constant temperature

Pressure of ideal gas at constant volume is proportional to _______.

The speed of sound in an ideal gas at a given temperature T is v. The rms speed of gas molecules at that temperature is v_rms. The ratio of the velocities v and v_rms for helium and oxygen gases are X and X' respectively. Then \(\frac{X}{X'}\) is equal to

Total impedance of a series LCR circuit varies with angular frequency of the AC source connected to it as shown in the graph. The quality factor Q of the series LCR circuit is

A charged particle is subjected to acceleration in a cyclotron as shown. The charged particle undergoes increase in its speed