List of top Physics Questions asked in JEE Main

A balloon has mass of 10 g in air The air escapes from the balloon at a uniform rate with velocity 4.5 cm/s If the balloon shrinks in 5 s completely Then, the average force acting on that balloon will be (in dyne)

Two projectile thrown at $30^{\circ}$ and $45^{\circ}$ with the horizontal respectively, reach the maximum height in same time The ratio of their initial velocities is

A screw gauge of pitch $05 \,mm$ is used to measure the diameter of uniform wire of length $68 \,cm$, the main scale reading is $15\, mm$ and circular scale reading is $7$. The calculated curved surface area of wire to appropriate significant figures is :[Screw gauge has $50$ divisions on the circular scale]

If the radius of earth shrinks by $2 \%$ while its mass remains same The acceleration due to gravity on the earth's surface will approximately :

A Carnot engine has efficiency of $50 \%$ .If the temperature of sink is reduced by $40^{\circ} C$, its efficiency increases by $30 \%$ .The temperature of the source will be :

Given below are two statements: 
Statement I: The average momentum of a molecule in a sample of an ideal gas depends on temperature. 
Statement II: The rms speed of oxygen molecules in a gas is $v$ If the temperature is doubled and the oxygen molecules dissociate into oxygen atoms, the rms speed will become $2 v$ In the light of the above statements, choose the correct answer from the options given below:

In the wave equation $y=05 \sin \frac{2 \pi}{\lambda}(400 t-x) m$ the velocity of the wave will be :

Two capacitors, each having capacitance $40 \mu F$ are connected in series The space between one of the capacitors is filled with dielectric material of dielectric constant $K$ such that the equivalence capacitance of the system became $24 \mu F$ The value of $K$ will be :

A wire of resistance $R_1$ is drawn out so that its length is increased by twice of its original length The ratio of new resistance to original resistance is:

As shown in the figure, a metallic rod of linear density \(0.45\ kg m^{-1}\) is lying horizontally on a smooth incline plane which makes an angle of 45° with the horizontal. The minimum current flowing in the rod required to keep it stationary, when \(0.15 T\) magnetic field is acting on it in the vertical upward direction, will be: {Use \(g = 10 m/s^2\)}

Three masses \(M =100 \,kg , m _1=10\, kg\) and \(m _2=20 \,kg\) are arranged in a system as shown in figure All the surfaces are frictionless and strings are inextensible and weightless The pulleys are also weightless and frictionless A force \(F\) is applied on the system so that the mass \(m _2\) moves upward with an acceleration of \(2\, ms ^{-2}\) The value of \(F\) is : (Take \(\text g=10\;ms^-2\))

\(B_X\) and \(B_Y\) are the magnetic field at the centre of two coils of two coils \(X\) and \(Y\) respectively, each carrying equal current If coil \(X\) has \(200\) turns and \(20\, cm\) radius and coil \(Y\) has \(400\) turns and \(20 \,cm\) radius, the ratio of \(B_X\) and \(B_Y\) is

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

\(7\) mole of certain monoatomic ideal gas undergoes a temperature increase of \(40\, K\) at constant pressure The increase in the internal energy of the gas in this process is (Given \(R =83\, JK ^{-1}\, mol ^{-1}\))

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:

The disintegration rate of a certain radioactive sample at any instant is $4250$ disintegrations per minute $10$ minutes later, the rate becomes $2250 $ disintegrations per minute The approximate decay constant is : (Take $\log _{10} 188=0274$ )

A parallel beam of light of wavelength $900 \,nm$ and intensity $100 \,Wm ^{-2}$ is incident on a surface perpendicular to the beam Tire number of photons crossing $1 \,cm ^2$ area perpendicular to the beam in one second is :

The equation $\lambda=\frac{1227}{ x } nm$ can be used to find the de-Brogli wavelength of an electron In this equation $x$ stands for : Where, $m =$ mass of electron $P =$ momentum of electron $K =$ Kinetic energy of electron $V=$ Accelerating potential in volts for electron

The half life period of a radioactive substance is 60 days The time taken for $\frac{7}{8}$ th of its original mass to disintegrate will be :

In the case of amplitude modulation to avoid distortion the modulation index $(\mu)$ should be:

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

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