JEE Main entrance exam Question Bank Solutions for Physics (JEE Main)

Two narrow bores of diameter 5.0 mm and 8.0 mm are joined together to form a U-shaped tube open at both ends. If this U-tube contains water, what is the difference in the level of the two limbs, of the tube?

[Take surface tension of water T = 7.3 × 10^-2 Nm^-1, angle of contact = 0, g = 10 ms^-2 and density of water = 1.0 × 10³ kgm^-3]

A soap bubble of radius 3 cm is formed inside another soap bubble of radius 6 cm. The radius of an equivalent soap bubble which has the same excess pressure as inside the smaller bubble with respect to the atmospheric pressure is ______ cm.

We have three identical perfectly black plates. The temperatures of first and third plate is T and 3T. What is the temperature of second plate if system is in equilibrium?

A liquid flows out drop by drop from a vessel through a vertical tube with an internal diameter of 2 mm, then the total number of drops that flows out during 10 grams of the liquid flow out ______. [Assume that the diameter of the neck of a drop at the moment it breaks away is equal to the internal diameter of tube and surface tension is 0.02 N/m].

A drop of water and a soap bubble have the same radii. Surface tension of soap solution is half of that of water. The ratio of excess pressure inside the drop and bubble is ______.

A coaxial cylinder made of glass is immersed in liquid of surface tension ' S'. Radius of inner and outer surface of cylinder are R1 and R2 respectively. Height till which liquid will rise is (Density of liquid is p):

A closely wounded circular coil of radius 5 cm produces a magnetic field of 37.68 × 10^-4 T at its center. The current through the coil is ______ A. [Given, number of turns in the coil is 100 and π = 3.14)

A metallic rod of length 20 cm is placed in North-South direction and is moved at a constant speed of 20 m/s towards East. The horizontal component of the Earth's magnetic field at that place is 4 × 10³ T and the angle of dip is 45°. The emf induced in the rod is ______ mV.

The total number of turns and cross-section area in a solenoid is fixed. However, its length L is varied by adjusting the separation between windings. The inductance of solenoid will be proportional to ______.

A boat is moving due east in a region where the earth's magnetic field is 5.0 × 10^-5 NA^-1 m^-1 due north and horizontal. The boat carries a vertical aerial 2 m long. If the speed of the boat is 1.50 ms^-1, the magnitude of the induced emf in the wire of aerial is ______.

A coil having n turns and resistance RΩ is connected with a galvanometer of resistance 4RΩ. This combination is moved in time t seconds from a magnetic field W₁ weber to W₂ weber. The induced current in the circuit is ______.

A polarizer - analyser set is adjusted such that the intensity of light coming out of the analyser is just 10% of the original intensity. Assuming that the polarizer - analyser set does not absorb any light, the angle by which the analyser need to be rotated further to reduce the output intensity to be zero, is ______.

In a U-tube, the radii of two columns are respectively r₁ and r₂. When a liquid of density ρ(θ = 0°) is filled in it, a level difference of h is observed on two arms, then the surface tension of the liquid is ______.

When an air bubble of radius r rises from the bottom to the surface of a lake, its radius becomes `(5r)/4`. Taking the atmospheric pressure to be equal to the 10 m height of the water column, the depth of the lake would approximately be ______.

(ignore the surface tension and the effect of temperature)

The excess pressure inside a liquid drop is 500 Nm^-2. If the radius of the drop is 2 mm, the surface tension of the liquid is x × 10^-3 Nm^-1. The value of x is ______.

A parallel beam of light is allowed to fall on a transparent spherical globe of diameter 30cm and refractive index 1.5. The distance from the centre of the globe at which the beam of light can converge is ______ mm.

The focal length f is related to the radius of curvature r of the spherical convex mirror by ______.

A bar magnet of length 14 cm is placed in the magnetic meridian with its north pole pointing towards the geographic north pole. A neutral point is obtained at a distance of 18 cm from the center of the magnet. If B_H = 0.4 G, the magnetic moment of the magnet is ______. (1 G = 10^–4T)

Car B overtakes car A at a relative speed of 40 ms^-1. How fast will the image of car B appear to move in the mirror of focal length 10 cm fitted in car A, when car B is 1.9 m away from car A?

Two short magnetic dipoles m₁ and m₂ each having a magnetic moment of 1 Am² are placed at points O and P respectively. The distance between OP is 1 metre. The torque experienced by the magnetic dipole m₂ due to the presence of m₁ is ______ × 10^-7 Nm.