List of top Physics Questions asked in JEE Main

A pole is vertically submerged in swimming pool, such that it gives a length of shadow 2.15 m within water when sunlight is incident at an angle of 30o with the surface of water. If swimming pool is filled to a height of 1.5 m, then the height of the pole above the water surface in centimeters is (n-w = 4/3) ____________
A person driving car at a constant speed of 15 m/s is approaching a vertical wall. The person notices a change of 40 Hz in the frequency of his car’s horn upon reflection from the wall. The frequency of horn is ____ Hz.
Two identical solid spheres each of mass 2 kg and radii 10 cm are fixed at the ends of a light rod. The separation between the centres of the spheres is 40 cm. The moment of inertia of the system about an axis perpendicular to the rod passing through its middle point is __________ \(× 10^{-3} \)kg-\(m^2\)

A parallel plate capacitor with plate area A and plate separation d is filled with a dielectric material of dielectric constant K = 4. The thickness of the dielectric material is x, where x < d. Let C1 and C2 be the capacitance of the system for \(x =\) \(\frac{1}{3}d\) and \(x=\frac{2}{3}d\), respectively. If C1 = 2μF, the value of C2 is _______ μF.

An ideal transformer with purely resistive load operates at 12 kV on the primary side. It supplies electrical energy to a number of nearby houses at 120 V. The average rate of energy consumption in the houses served by the transformer is 60 kW. The value of resistive load (Rs) required in the secondary circuit will be ________ mΩ.
A particle of mass 10 g moves in a straight line with retardation 2x, where x is the displacement in SI units. Its loss of kinetic energy for above displacement is \((10/x)^{-n}\)J. The value of n will be ____________
The radius of fifth orbit of the Li++ is __________ × 10^-12 m.
Take : radius of hydrogen atom = 0.51 Å
The length of a metallic wire is increased by 20% and its area of cross section is reduced by 4%. The percentage change in resistance of the metallic wire is ______
A steel rod bas a radius of 20 mm and a length of 2.0 m. A force of 62.8 kN stretches it along its length. Young's modulus of steel is 2.0 × 10^{11} N/m^2 . The longitudinal strain produced in the wire is _______ × 10^{-5}
Two identical circular wires of radius 20 cm and carrying current \(\sqrt2 \)A are placed in perpendicular planes as shown in figure. The net magnetic field at the centre of the circular wires is _________ × 10^{-8} T.
 
Two identical circular wires of radius 20 cm

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. 
Assertion (A): Range of a horizontal projectile is maximum when angle of projection is \(θ = 45°\).
Reason (R): Range is maximum when \(sin\ (2θ)=1\).
In the light of the above statements, choose the correct answer from the options given below

The induced emf can be produced in a coil by
A. moving the coil with uniform speed inside uniform magnetic field 
B. moving the coil with non uniform speed inside uniform magnetic field 
C. rotating the coil inside the uniform magnetic field 
D. changing the area of the coil inside the uniform magnetic field 
Choose the correct answer from the options given below :
A monochromatic light wave with wavelength λ1 and frequency ν1, in air, enters another medium. If the angle of incidence and angle of refraction at the interface are 45° and 30° respectively, then the wavelength λ2 and frequency ν2 of the refracted wave are:

A planet has double the mass of the earth. Its average density is equal to that of the earth. An object weighing W on earth will weigh on that planet:

For the plane electromagnetic wave given by \(E = E_o sin (ωt-kx)\) and \(B = B_o sin ( ωt-kx)\), the ratio of average electric energy density to average magnetic energy density is
The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is
energy level
The fundamental frequency of vibration of a string stretched between two rigid support is 50 Hz. The mass of the string is 18 g and its linear mass density is 20 g/m. The speed of the transverse waves so produced in the string is_______ ms-1.
The number of air molecules per cm3 increased from 3 × 1019 to 12 × 1019. The ratio of collision frequency of air molecules before and after the increase in the number respectively is :
For designing a voltmeter of range 50 V and an ammeter of range 10 mA using a galvanometer which has a coil of resistance 54Ω showing a full scale deflection for 1 mA as in figure.
voltmeter of range 50 V and an ammeter
(A) for voltmeter R ≈ 50 kΩ  
(B) for ammeter r ≈ 0.2Ω  
(C) for ammeter r ≈ 6Ω  
(D) for voltmeter R ≈ 5 kΩ (E) for voltmeter R ≈ 500Ω 
Choose the correct answer from the options given below :
 
A 12V battery connected to a coil of resistance 6Ω through a switch, drives a constant current in the circuit. The switch is opened in 1ms. The emf induced across the coil is 20V. The inductance of the coil is:

Match the list-I with list-II and choose the correct option.

 List-I List-II
(A).Microwave(P).1 nm - 400nm
(B).Ultraviolet(Q).1 nm - 1nm
(C).X-rays(R).2.5 µm - 750nm
(D).Infrared(S).1 µm - 1nm
A single slit of width a is illuminated by a monochromatic light of wavelength 600 nm. The value of 'a' for which first minimum appears at θ=30° on the screen will be :

The half-life of a radioactive nucleus is 5 years. The fraction of the original sample that would decay in 15 years is:

In the given circuit, the current (I) through the battery will be
the current (I) through the battery
Height of the receiving and transmitting antenna in communication of a signal are 245 m and 180 m respectively. Find the maximum distance between the two antennas for proper communication.