List of top Physics Questions asked in JEE Main

Three Carnot engines operate in series between a heat source at a temperature $T_1$ and a heat sink at temperature $T_4$ (see figure). There are two other reservoirs at temperature $T_2$, and $T_3$, as shown, with $T_2 > T_2 > T_3 > T_4$ . The three engines are equally efficient if:
Determine the charge on the capacitor in the following circuit :
One of the two identical conducting wires of length $L$ is bent in the form of a circular loop and the other one into a circular coil of $N$ identical turns. If the same current is passed in both, the ratio of the magnetic field at the central of the loop $(B_L)$ to that at the centre of the coil $(B_C)$ , i.e., $R \frac{B_L}{B_C}$ will be
Determine the electric dipole moment of the system of three charges, placed on the vertices of an equilateral triangle, as shown in the figure:
A solid sphere and solid cylinder of identical radii approach an incline with the same linear velocity (see figure). Both roll without slipping all throughout. The two climb maximum heights $h_{sph}$ and $h_{cyl}$ on the incline. The ratio $\frac{h_{sph}}{h_{cyl}}$ is given by :
Water flows into a large tank with flat bottom at the rate of $10^{-4} \; m^3 s^{-1}$. Water is also leaking out of a hole of area $1\, cm^2$ at its bottom. If the height of the water in the tank remains steady, then this height is :
A metal ball of mass $0.1\, kg$ is heated upto $500^{\circ}C$ and dropped into a vessel of heat capacity $800 \; JK^{-1}$ and containing $0.5\, kg$ water. The initial temperature of water and vessel is $30^{\circ}C$. What is the approximate percentage increment in the temperature of the water ? [Specific Heat Capacities of water and metal are, respectively, $4200 \; Jkg^{-1} K^{-1}$ and $400 \; JKg^{-1} K^{-1}$]
A galvanometer, whose resistance is $50\, ohm$, has $25$ divisions in it. When a current of $4 \times 10^{-4}$ A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range $2.5\, V$, it should be connected to a resistance of:
A body of mass $1\, kg$ falls freely from a height of $100\, m$ on a platform of mass $3\, kg$ which is mounted on a spring having spring constant $k = 1.25 \times 10^6 \; N/m$. The body sticks to the platform and the spring's maximum compression is found to be $x$. Given that $g = 10 \; ms^{-2}$, the value of $x$ will be close to :
Figure shown a $DC$ voltage regulator circuit, with a Zener diode of breakdown voltage = $6V$. If the unregulated input voltage varies between $10\, V$ to $16\, V$, then what is the maximum Zener current ?
A block of mass $m$, lying on a smooth horizontal surface, is attached to a spring (of negligible mass) of spring constant $k$. The other end of the spring is fixed, as shown in the figure. The block is initally at rest in its equilibrium position. If now the block is pulled with a constant force $F$, the maximum speed of the block is :
A paramagnetic substance in the form of a cube with sides $1\, cm$ has a magnetic dipole moment of $20 \times 10^{-6} \; J/T$ when a magnetic intensity of $60 \times 10^3 \; A/m$ is applied. Its magnetic susceptibility is :
In the figure, given that $V_{BB}$ supply can vary from $0$ to $5.0 \,V, V_{CC} = 5\,V, \beta_{dc} = 200, R_B = 100 \,k\,\Omega, R_C=l\, k\Omega$ and $V_{BE}=1.0\, V$, The minimum base current and the input voltage at which the transistor will go to saturation, will be, respectively :
If $'M'$ is the mass of water that rises in a capillary tube of radius $'r'$, then mass of water which will rise in a capillary tube of radius $'2r'$ is :
A homogeneous solid cylindrical roller of radius $R$ and mass $M$ is pulled on a cricket pitch by a horizontal force. Assuming rolling without slipping, angular acceleration of the cylinder is :
Two materials having coefficients of thermal conductivity '3K' and 'K' and thickness 'd' and '3d', respectively, are joined to form a slab as shown in the figure. The temperatures of the outer surfaces are $'\theta_2'$ and $' \theta_1'$ respectively, $(\theta_2 > \theta_1)$. The temperature at the interface is :-
A circular coil having $N$ turns and radius $r$ carries a current $I$. It is held in the $XZ$ plane in a magnetic field $B \hat{i}$ . The torque on the coil due to the magnetic field is :
Two electric dipoles, $A, B$ with respective dipole moments $\vec{d}_A = - 4 \,qa \,\hat{i}$ and $\vec{d}_B = - 2 \,qa\, \hat{i}$ placed on the x-axis with a separation $R$, as shown in the figure The distance from $A$ at which both of them produce the same potential is :
A steel wire having a radius of $2.0\, mm$, carrying a load of $4 \,kg$, is hanging from a ceiling. Given that $g = 3.1 \; \pi \; ms^{-2}$, what will be the tensile stress that would be developed in the wire ?
A particle is executing simple harmonic motion (SHM) of amplitude A, along the $x$-axis, about $x = 0$. When its potential Energy (PE) equals kinetic energy (KE), the position of the particle will be :
An electron, moving along the x-axis with an initial energy of $100\, eV$, enters a region of magnetic field $\vec{B} \, = (1.5 \times 10^{-3} T) \hat{k}$ at $S$ (See figure). The field extends between $x = 0$ and $x = 2\, cm$. The electron is detected at the point $Q$ on a screen placed $8\, cm$ away from the point $S$. The distance $d$ between $P$ and $Q$ (on the screen) is : (electron's charge = $1.6 \times 10^{-19}C.$ mass of electron = $9.1 \times 10^{-31}kg)$
A series $AC$ circuit containing an inductor $(20\, mH)$, a capacitor $(120 \; \mu F) $and a resistor $(60 \Omega)$ is driven by an AC source of $24\, V/50 \,Hz$. The energy dissipated in the circuit in $60\, s$ is :
A magnet of total magnetic moment $10^{-2} \hat{i} \; A-m^2$ is placed in a time varying magnetic field, $B \hat{i} (\cos t\omega t)$ where $B = 1 $Tesla and $\omega = 0.125 \; rad/s$. The work done for reversing the direction of the magnetic moment at $t = 1$ second, is :
A rod, of length $L$ at room temperature and uniform area of cross section $A$, is made of a metal having coefficient of linear expansion $\alpha / {^{\circ}C}$. It is observed that an external compressive force $F$, is applied on each of its ends, prevents any change in the length of the rod, when its temperature rises by $\Delta T K$. Young's modulus, $Y$, for this metal is :
A boy's catapult is made of rubber cord which is $42\, cm$ long, with $6\, mm$ diameter of cross-section and of negligible mass. The boy keeps a stone weighing $0.02\,kg$ on it and stretches the cord by $20\, cm$ by applying a constant force. When released, the stone flies off with a velocity of $20\, ms^{-1}$. Neglect the change in the area of cross-section of the cord while stretched. The Young's modulus of rubber is closest to: