List of top Physics Questions asked in JEE Main

The current density in a cylindrical wire of radius \(r = 4.0\) mm is \(1.0 \times 10^6\) \(A/m^2\). The current through the outer portion of the wire between radial distances \(\frac{r}{2}\) and \(r\) is \(xπ\) \(A\); where \(x\) is _________.

Two coils require 20 minutes and 60 minutes respectively to produce same amount of heat energy when connected separately to the same source. If they are connected in parallel arrangement to the same source; the time required to produce same amount of heat by the combination of coils, will be ___ min.

Choose the correct answer:

1. Two balls A and B are placed at the top of 180 m tall tower. Ball A is released from the top at t = 0 s. Ball B is thrown vertically down with an initial velocity u at t = 2 s. After a certain time, both balls meet 100 m above the ground. Find the value of u in ms–1 [use g = 10 ms–2]

Two light beams of intensities in the ratio of 9 : 4 are allowed to interfere. The ratio of the intensity of maxima and minima will be:
Which of the following statement is correct ?
At time t = 0 a particle starts travelling from a height \(7\hat z cm\) in a plane keeping \(z\) coordinate constant. At any instant time it's position along the \(x\) and \(y\) directions are defined as \(3t\) and \(5t^3\) respectively. At \(t = 1s\) acceleration of the particle will be
The equivalent resistance between points A and B in the given network is:
 equivalent resistance between points A and B in the given network
Sun light falls normally on a surface of area \(36 cm^2\) and exerts an average force of \(7.2 × 10^{–9} N\) within a time period of \(20 minutes\). Considering a case of complete absorption, the energy flux of incident light is
If the charge on a capacitor is increased by 2 C, the energy stored in it increases by 44%. The original charge on the capacitor is (in C)
Two parallel, long wires are kept 0.20 m apart in vacuum, each carrying current of x A in the same direction. If the force of attraction per meter of each wire is \(2 \times 10^{–6} \text{N}\), then the value of x is approximately:
A disc with a flat small bottom beaker placed on it at a distance R from its center is revolving about an axis passing through the center and perpendicular to its plane with an angular velocity ω. The coefficient of static friction between the bottom of the beaker and the surface of the disc is μ. The beaker will revolve with the disc if :
The difference of speed of light in the two media A and B(υA – υB) is 2.6 × 107 m/s. If the refractive index of medium B is 1.47, then the ratio of refractive index of medium B to medium A is: (Given: speed of light in vacuum C = 3 × 108 ms–1)

The electric field in an electromagnetic wave is given by \(E = 56.5\ sin ω(t – \frac xc)\ NC^{–1}\). Find the intensity of the wave if it is propagating along x-axis in the free space. (Given \(∈_0 = 8.85 × 10^{–12} C^2N^{–1}m^{–2}\))

A 100 g of iron nail is hit by a \(1.5\) \(kg\) hammer striking at a velocity of \(60 \;ms^{–1}\). What will be the rise in the temperature of the nail if one fourth of energy of the hammer goes into heating the nail?
[Specific heat capacity of iron = \(0.42\; Jg^{–1} °C^{–1}\)]
A parallel plate capacitor is made up of stair like structure with a plate area A of each stair and that is connected with a wire of length b, as shown in the figure. The capacitance of the arrangement is \(\frac{x}{15} \frac{ε_0A}{b}\), the value of \(x\) is ______?
A parallel plate capacitor is made up of stair like structure with a plate area A of each stair and that is connected with a wire of length b
All resistances in figure are 1 Ω each. The value of current ‘I‘ is \((\frac{a}{5})\) A. The value of a is _______.
value of current
A screw gauge of pitch 0.5 mm is used to measure the diameter of uniform wire of length 6.8 cm, the main scale reading is 1.5 mm and circular scale reading is 7. The calculated curved surface area of wire to appropriate significant figures is :
[Screw gauge has 50 divisions on its circular scale.]
A metal surface is illuminated by a radiation of wavelength 4500 Å. The rejected photo-electron enters a constant magnetic field of 2 mT making an angle of 90° with the magnetic field. If it starts revolving in a circular path of radius 2 mm, the work function of the metal is approximately:

Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R. 

Assertion A: Two identical balls A and B thrown with same velocity ’u’ at two different angles with horizontal attained the same range R. If A and B reached the maximum height h1 and h2 respectively, then 

\(R=\sqrt{4ℎ1ℎ2}.\)

Reason R: Product of said heights.

\(h_1h_2=(\frac{u^2sin^2θ}{2g}).(\frac{u^2cos^2θ}{2g})\)

A travelling microscope is used to determine the refractive index of a glass slab. If 40 divisions are there in 1 cm on main scale and 50 Vernier scale divisions are equal to 49 main scale divisions, then least count of the travelling microscope is _______× 10–6 m.
The effective current I in the given circuit at very high frequencies will be ______ A.
The effective current I in the given circuit
A signal of 100 THz frequency can be transmitted with maximum efficiency by :
A metallic conductor of length 1 m rotates in a vertical plane parallel to east-west direction about one of its end with angular velocity 5 rad s–1. If the horizontal component of earth’s magnetic field is 0.2 × 10–4 T, then emf induced between the two ends of the conductor is:
The graph between \(\frac 1u\) and \(\frac 1v\) for a thin convex lens in order to determine its focal length is plotted as shown in the figure. The refractive index of lens is 1.5, and its both the surfaces have the same radius of curvature R. The value of R will be______cm.
(where u = object distance, v = image distance)
The graph between 1/u and 1/v for a thin convex lens
A force on an object of mass \(100\ g\) is \((10\hat i+5\hat j)\ N\). The position of that object at \(t = 2s\) is \((a\hat i+b\hat j)\ m\) after starting from rest. The value of \(\frac ab\) will be _______ .