List of top Questions asked in JEE Main

The magnetic field of a plane electromagnetic wave is given by $\vec{ B }=2 \times 10^{-8} \sin \left(05 \times 10^3 x +15 \times 10^{11} t \right) \hat{ j } T$ The amplitude of the electric field would be

In a series LR circuit $X_L=R$ and power factor of the circuit is $P _1$ When capacitor with capacitance $C$ such that $X _{ L }= X _{ C }$ is put in series, the power factor becomes $P _2$ The ratio $\frac{ P _1}{ P _2}$ is

A charge particle is moving in a uniform magnetic field $(2 \hat{ i }+3 \hat{ j }) T$ If it has an acceleration of $(\alpha \hat{i}-4 \hat{j}) m / s ^2$, then the value of $\alpha$ will be

The total charge on the system of capacitance $C _1=1\, \mu F , C _2=2 \,\mu F , C _3=4 \,\mu F $ and $C _4=3\, \mu F$ connected in parallel is (Assume a battery of $20 \,V$ is connected to the combination)

When a particle executes simple Harmonicmotion, the nature of graph of velocity asfunction of displacement will be :

Consider two containers A and B containing monoatomic gases at the same Pressure (P), Volume (V) and Temperature (T). The gas in A is compressed isothermally to $\frac{1}{8}$ of its original volume while the gas in B is com pressed adiabatically to $\frac{1}{8}$ of its original volume. The ratio of final pressure of gas in B to that of gas in A is

A water drop of radius $1 \,cm$ is broken into $729$ equal droplets If surface tension of water is $75 \,dync / cm$, then the gain in surface energy upto first decimal place will be : [Given $\pi=314]$

The percentage decrease in the weight of a rocket, when taken to a height of $32 \,km$ above the surface of earth will, be : (Radius of earth $=6400 \,km$ )

The motion of a simple pendulum executing S.H.M. is represented by the following equation. y = A sin(πt + φ), where time is measured in second. The length of pendulum is

A vessel contains 16 g of hydrogen and 128 g of oxygen at standard temperature and pressure. The volume of the vessel in cm³ 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

Given below are two statements:

Statement I: The electric force changes the speed of the charged particle and hence changes its kinetic energy; whereas the magnetic force does not change the kinetic energy of the charged particle.
Statement II: The electric force accelerates the positively charged particle perpendicular to the direction of electric field. The magnetic force accelerates the moving charged particle along the direction of magnetic field.

In the light of the above statements, choose the most appropriate answer from the options given below:

Two streams of photons, possessing energies equal to five and ten times the work function of metal are incident on the metal surface successively. The ratio of maximum velocities of the photoelectron emitted, in the two cases respectively, will be

In the given figure, the block of mass m is dropped from the point ‘A’. The expression for kinetic energy of block when it reaches point ‘B’ is

A radioactive sample decays 7/8 times its original quantity in 15 minutes. The half-life of the sample is

A block of mass M placed inside a box descends vertically with acceleration ‘a’.The block exerts a force equal to one-fourth of its weight on the floor of the box.
The value of ‘a’ will be

If the electric potential at any point (x, y, z)m in space is given by V = 3x² volt. The electric field at the point (1, 0, 3)m will be

An npn transistor with current gain $β = 100$ in common emitter configuration is shown in the figure. The output voltage of the amplifier will be

The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of 2 Ω. The value of internal resistance of each cell is

A person can throw a ball upto a maximum range of 100 m. How high above the ground he can throw the same ball?

The vernier constant of Vernier callipers is 0.1 mm and it has zero error of (–0.05) cm. While measuring diameter of a sphere, the main scale reading is 1.7 cm and coinciding vernier division is 5. The corrected diameter will be ________× 10^–2 cm.

A small spherical ball of radius 0.1 mm and density 10⁴ kg m^–3 falls freely under gravity through a distance h before entering a tank of water. If, after entering the water the velocity of ball does not change and it continue to fall with same constant velocity inside water, then the value of h will be ______ m.
(Given g = 10 ms^–2, viscosity of water = 1.0 × 10^–5 N-sm^–2).

In an experiment to determine the velocity of sound in air at room temperature using a resonance tube, the first resonance is observed when the air column has a length of 20.0 cm for a tuning fork of frequency 400 Hz is used. The velocity of the sound at room temperature is 336 ms^–1. The third resonance is observed when the air column has a length of ______ cm.

Two resistors are connected in series across a battery as shown in figure. If a voltmeter of resistance 2000 Ω is used to measure the potential difference across 500 Ω resistor, the reading of the voltmeter will be _____ V.

A potential barrier of 0.4 V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 × 10⁵ms^–1. The speed with which electrons enters the p side will be
$\frac{x}{3} × 10^5$ ms^-1
the value of x is _________.
(Give mass of electron = 9 × 10^–31 kg, charge on electron = 1.6 × 10^–19 C)