List of top Questions asked in JEE Main

The elongation of a wire on the surface of the earth is 10^–4m. The same wire of same dimensions is elongated by 6 × 10^–5m on another planet. The acceleration due to gravity on the planet will be ___ ms^–2. (Take acceleration due to gravity on the surface of earth = 10 ms^–2)

A body of mass m is projected with velocity λv_e in vertically upward direction from the surface of the earth into space. It is given that v_e is escape velocity and λ< 1. If air resistance is considered to be negligible, then the maximum height from the centre of earth, to which the body can go, will be:
(R : radius of earth)

Two objects of equal masses placed at certain distance from each other attracts each other with a force of F. If one-third mass of one object is transferred to the other object, then the new force will be

As shown in the figure, after passing through the medium 1. The speed of light v₂ in medium 2 will be: (Given $c = 3 \times 10^8 ms^{-1}$)

In normal adjustment, for a refracting telescope, the distance between objective and eye piece is $30\,cm$ The focal length of the objective, when the angular magnification of the telescope is 2, will be:

A light wave travelling linearly in a medium of dielectric constant 4, incidents on the horizontal interface separating medium with air. The angle of incidence for which the total intensity of incident wave will be reflected back into the same medium will be:
(Given : relative permeability of medium μ_r= 1)

A signal of 100 THz frequency can be transmitted with maximum efficiency by :

The difference of speed of light in the two media A and B(υ_A – υ_B) 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 × 10⁸ms^–1)

A parallel beam of light of wavelength 900 nm and intensity 100 Wm^–2 is incident on a surface perpendicular to the beam. The number of photons crossing 1 cm^–2 area perpendicular to the beam in one second is

The refracting angle of prism is A and refractive index of material of prism is $\cot \frac{A}{2}$ The angle of minimum deviation is

The aperture of the objective is 24.4 cm. The resolving power of this telescope, if a light of wavelength 2440 Å is used to see the object will be:

A small bulb is placed at the bottom of a tank containing water to a depth of √7 m. The refractive index of water is 4/3. The area of the surface of water through which light from the bulb can emerge out is xπ m². The value of x is ________.

The power of a lens (biconvex) is $1.25 m^{–1}$ in particular medium. Refractive index of the lens is $1.5$, and the radii of curvature are $20 cm$ and $40 cm$, respectively. The refractive index of surrounding medium

A thin prism of angle 6° and refractive index for yellow light (nY)1.5 is combined with another prism of angle 5° and nY = 1.55. The combination produces no dispersion. The net average deviation (δ) produced by the combination is (1/x)°. The value of x is __________.

A microscope was initially placed in air (refractive index 1). It is then immersed in oil (refractive index 2). For a light whose wavelength in air is λ, calculate the change of microscope’s resolving power due to oil and choose the correct option.

A wire X of length 50 cm carrying a current of 2 A is placed parallel to a long wire Y of length 5 m. The wire Y carries a current of 3 A. The distance between two wires is 5 cm and currents flow in the same direction. The force acting on the wire Y is

A wire X of length 50 cm carrying a current of 2 A is placed parallel to a long wire Y of length 5 m

A 8 V Zener diode along with a series resistance R is connected across a 20 V supply (as shown in the figure). If the maximum Zener current is 25 mA, then the minimum value of R will be ____ Ω.

A 8 V Zener diode along with a series resistance R is connected across a

Let
$x = \begin{bmatrix} 1 \\ 1 \\ 1 \end{bmatrix}$ and $A = \begin{bmatrix} -1 & 2 & 3 \\ 0 & 1 & 6 \\ 0 & 0 & -1 \end{bmatrix}$
For k ∈ N, if X’A^kX = 33, then k is equal to ____ .

Let P(a, b) be a point on the parabola y² = 8x such that the tangent at P passes through the centre of the circle x² + y² – 10x – 14y + 65 = 0. Let A be the product of all possible values of a and B be the product of all possible values of b. Then the value of A + B is equal to

A uniform heavy rod of mass $20$ kg, cross sectional area $0.4$ $m^2$ and length $20$ $m$ is hanging from a fixed support. Neglecting the lateral contraction, the elongation in the rod due to its own weight is $x × 10^{–9}$ $m$. The value of $x$ is _____(Given Young’s modulus $Y = 2 × 10^{11} Nm^{–2}$and g = $10\; ms^{–2})$

The ratio of specific heats

$(\frac{c_p}{c_v}) $

in terms of degree of freedom (f) is given by:

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : At 10°C, the density of a 5 M solution of KCl [atomic masses of K & Cl are 39 & 35.5 g $mol^{–1}$ respectively], is ‘x’ g $ml^{–1}$. The solution is cooled to –21°C. The molality of the solution will remain unchanged.
Reason (R) : The molality of a solution does not change with temperature as mass remains unaffected with temperature.
In the light of the above statements, choose the correct answer from the options given below.

A 42.12% (w, v) solution of NaCl causes precipitation of a certain sol in 10 hours. The coagulating value of NaCl for the sol is
[Given : Molar mass : Na = 23.0 g mol^–1; Cl = 35.5 g mol^–1]

Compound A contains 8.7% Hydrogen, 74% Carbon and 17.3% Nitrogen. The molecular formula of the compound is,
Given : Atomic masses of C, H and N are 12, 1 and 14 amu, respectively.
The molar mass of the compound A is 162g mol^–1.

Given below are two statements :
Statement-I : For KI, molar conductivity increases steeply with dilution.
Statement-II : For carbonic acid, molar conductivity increases slowly with dilution.
In the light of the above statements, choose the correct answer from the options given below :