List of top Physics Questions asked in JEE Main

A solid sphere (A) of mass \(5m\) and a spherical shell (B) of mass \(m\), both having the same radius, are placed on a rough surface. When a force of same magnitude is applied tangentially at the highest points of \(A\) and \(B\), they start rolling without slipping with accelerations \(a_A\) and \(a_B\) respectively. The ratio of \(a_A\) and \(a_B\) is _____.

The percentage error in the calculated volume of a sphere, if there is \(2%\) error in its diameter measurement, is _____.

A body of mass \(1\,\text{kg}\) moves along a straight line with a velocity \(v=2x^2\). The work done by the body during displacement from \(x=0\) to \(x=5\,\text{m}\) is _____ J.

A circular loop of radius 20 cm and resistance 2 \(\Omega\) is placed in a time varying magnetic field \( \vec{B} = (2t^2 + 2t + 3) \text{ T} \). At \( t=0 \), for the plane of the loop being perpendicular to the magnetic field and, the induced current in the loop at \( t = 3 \text{ s} \) is \( \alpha/50 \text{ A} \). The value of \( \alpha \) is \dots (Take \( \pi = 22/7 \))}

When an external resistance of 5 \(\Omega\) is connected across terminals of a cell, a current of 0.25 A flows through it. When the 5 \(\Omega\) resistor is replaced by a 2 \(\Omega\) resistor, a current of 0.5 A flows through it. The internal resistance of the cell is \dots \(\Omega\).

In a semiconductor p-n diode, the doping concentrations on p-side and n-side are \( 10^{15} \text{ atoms/cm}^3 \) and \( 10^{18} \text{ atoms/cm}^3 \), respectively. Which one of the following statements is true?

The heat extracted out of \( x \) gram of water initially at \( 50^\circ\text{C} \) to cool it down to \( 0^\circ\text{C} \) is sufficient to evaporate \( (1000-x) \) gram of water also initially at \( 50^\circ\text{C} \). The value of \( x \) (closest integer) is \dots
(Take latent heat of water 2256 kJ/kg, specific heat capacity of water 4200 J/kg$\cdot$K)}

An electron is travelling with a velocity \( v \) in free space and when it enters a medium, its velocity is reduced by 20%. The de Broglie wavelength of electron in the medium is \( \alpha\lambda_o \), where \( \lambda_o \) is its de Broglie wavelength in free space. The value of \( \alpha \) is \dots

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) :} The electromagnetic wave exerts pressure on the surface on which they are allowed to fall.
Reason (R) :} There is no mass associated with the electromagnetic waves.
In the light of the above statements, choose the correct answer from the options given below :

A metal rod of length $L$ rotates about one end at origin with a uniform angular velocity $\omega$. The magnetic field radially falls off as $B(r) = B_o e^{-\lambda r}$; $\lambda$ being a positive constant. The emf induced (neglecting the centripetal force on electrons in the rod) is :

A thin convex lens and a thin concave lens are kept in contact and are co-axial. Which of the following statements is correct for this combination of two lenses ?

Match List - I with List - II.

A particle of charge $q$ and mass $m$ is projected from origin with an initial velocity $\vec{v} = \left( \frac{v_o}{\sqrt{2}} \hat{x} + \frac{v_o}{\sqrt{2}} \hat{y} \right)$. There exists a uniform magnetic field $\vec{B} = B_o \hat{z}$ and a space varying electric field $\vec{E} = E_o e^{-\lambda x} \hat{x}$ within the region $0 \le x \le L$. After travelling a distance such that $x$-coordinate has changed from $x=0$ to $x=L$, the change in the kinetic energy is \dots

A wheel initially at rest is subjected to a uniform angular acceleration about its axis. In the first 2 s it rotates through an angle $\theta_1$ and in the next 2 s it rotates through an angle $\theta_2$. The ratio $\frac{\theta_2}{\theta_1}$ is :

The velocity ($v$) versus time ($t$) plot of a particle is shown in the figure,for a time interval of 40 s. The total distance travelled by the particle and the average velocity during this period are, respectively :}

Match List - I with List - II (where h is Planck's constant, G is gravitational constant and c is speed of light):

A mass of 1 kg is kept on a inclined plane with $30^\circ$ inclination with respect to horizontal plane and it is at rest initially. Then the whole assembly is moved up with constant velocity of 4 m/s. The work done by the frictional force in time 2 s is \dots J. (Take $g = 10 \text{ m/s}^2$)

In an experiment to determine the resistance of a given wire using Ohm's law, the voltmeter and ammeter readings are noted as 10 V and 5 A, respectively. The least counts of voltmeter and ammeter are 500 mV and 200 mA, respectively. The estimated error in the resistance measurement is :

The charged particle moving in a uniform magnetic field of \((3\hat{i} + 2\hat{j}) \text{ T}\) has an acceleration \((4\hat{i} - \frac{x}{2}\hat{j}) \text{ m/s}^2\). The value of \(x\) is ____.

A transverse wave on a string is described by \(y = 3\sin(36t + 0.018x + \pi/4)\), where \(x, y\) are in cm and \(t\) in seconds. The least distance between the two successive crests in the wave is ____ \text{cm}. (Nearest integer) (\(\pi = 3.14\))}

In the given circuit below inductance values of \(L_1, L_2\) and \(L_3\) are same. The magnetic energy stored in the entire circuit is \((U_t)\) and that stored in the \(L_2\) inductor is \((U_j)\). \(U_t / U_j\) is ____. (Ignore the mutual inductance if any).

A cube has side length \(5 \text{ cm}\) and modulus of rigidity \(10^5 \text{ N/m}^2\). The displacement produced by a force of \(10 \text{ N}\) in the upper face of the cube is ____ \text{mm}.

Two wires as shown in the figure below, made of steel and have breaking stress of $12 \times 10^8 \text{ N/m}^2$. Area of cross-section of upper wire is $0.008 \text{ cm}^2$ and of lower wire is $0.004 \text{ cm}^2$. The maximum mass that can be added to pan without breaking any wire is _________ kg. (take $g = 10 \text{ m/s}^2$)}

A compound microscope is designed with two symmetric biconvex lenses. The objective lens is cut vertically, creating two identical plano-convex lenses. One of them is used in place of original objective lens. To retain same magnification keeping the object distance unchanged, the tube length has to be:

An a.c. source of angular frequency $\omega$ is connected across a resistor $R$ and a capacitor $C$ in series. The current is observed as $I$. Now the frequency of the source is changed to $\omega/4$, (keeping the voltage unchanged) the current is found to be $I/3$. The ratio of resistance to reactance at frequency $\omega$ is: