List of top Physics Questions asked in JEE Main

A signal \(A\cos\omega t\) is transmitted using \(v_0\sin\omega_0 t\) as carrier wave. The correct amplitude modulated (AM) signal is

An NPN transistor is used in common emitter configuration as an amplifier with \(1\ \mathrm{k}\Omega\) load resistance. Signal voltage of 10 mV is applied across the base-emitter. This produces a 3 mA change in the collector current and \(15\mu\mathrm{A}\) change in the base current of the amplifier. The input resistance and voltage gain are :

The stream of a river is flowing with a speed of 2 km/h. A swimmer can swim at a speed of 4 km/h. What should be the direction of the swimmer with respect to the flow of the river to cross the river straight ?

A simple pendulum oscillating in air has period \(T\). The bob of the pendulum is completely immersed in a non-viscous liquid. The density of the liquid is 1/16 th of the material of the bob. If the bob is inside liquid all the time, its period of oscillation in this liquid is :

A capacitor with capacitance \(5\mu\mathrm{F}\) is charged to \(5\mu\mathrm{C}\). If the plates are pulled apart to reduce the capacitance to \(2\mu\mathrm{F}\), how much work is done ?

The total number of turns and cross-section area in a solenoid is fixed. However, its length \(L\) is varied by adjusting the separation between windings. The inductance of solenoid will be proportional to :

A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of \(\theta\), where \(\theta\) is the angle by which it has rotated, is given as \(k\theta^2\). If its moment of inertia is \(I\) then the angular acceleration of the disc is :

The electric field of light wave is given as
\(\vec{E}=10^{-3}\cos\left(\frac{2\pi x}{5\times10^{-7}}-2\pi\times6\times10^{14}t\right)\hat{x}\ \frac{\mathrm{N}}{C}\)
This light falls on a metal plate of work function 2 eV. The stopping potential of the photoelectrons is :
Given, \(E\) (in eV) \(=12375/\lambda\) (in \(\mathrm{\AA}\))

The figure shows a Young's double slit experimental setup. It is observed that when a thin transparent sheet of thickness \(t\) and refractive index \(\mu\) is put in front of one of the slits, the central maximum gest shifted by a distance equal to \(n\) fringe widths. If the wavelength of light used is \(\lambda\), \(t\) will be :

The following bodies are made to roll up (without slipping) the same inclined plane from a horizontal plane. : (i) a ring of radius \(R\), (ii) a solid cylinder of radius \(R/2\) and (iii) a solid sphere of radius \(R/4\). If in each case, the speed of the centre of mass at the bottom of the incline is same, the ratio of the maximum heights they climb is :

In the density measurement of a cube, the mass and edge length are measured as \((10.00\pm0.10)\) kg and \((0.10\pm0.01)\) m, respectively. The error in the measurement of density is :

A system of three charges are placed as shown in the figure :

If \(D \gg d\), the potential energy of the system is best given by :

A rectangular coil (Dimension \(5\ \mathrm{cm} \times 2.5\ \mathrm{cm}\)) with 100 turns, carrying a current of 3 A in the clock-wise direction is kept centered at the origin and in the X-Z plane. A magnetic field of 1 T is applied along X-axis. If the coil is tilted through \(45^\circ\) about Z-axis, then the torque on the coil is :

A concave mirror for face viewing has focal length of 0.4 m. The distance at which you hold the mirror from your face in order to see your image upright with a magnification of 5 is :

A moving coil galvanometer has resistance \(50\ \Omega\) and it indicates full deflection at 4 mA current. A voltmeter is made using this galvanometer and a \(5\ \mathrm{k\Omega}\) resistance. The maximum voltage, that can be measured using this voltmeter, will be close to :

A wire of resistance \(R\) is bent to form a square ABCD as shown in the figure. The effective resistance between E and C is : (E is mid-point of arm CD)

A string is clamped at both the ends and it is vibrating in its 4th harmonic. The equation of the stationary wave is \(Y = 0.3\sin(0.157x)\cos(200\pi t)\). The length of the string is : (All quantities are in SI units.)

The pressure wave, \(P = 0.01\sin[1000t - 3x]\ \mathrm{Nm^{-2}}\), corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is \(0^\circ\mathrm{C}\). On some other day, when temperature is T, the speed of sound produced by the same blade and at the same frequency is found to be \(336\ \mathrm{ms^{-1}}\). Approximate value of T is

For a given gas at 1 atm pressure, rms speed of the molecule is 200 m/s at \(127^\circ\mathrm{C}\). At 2 atm pressure and at \(227^\circ\mathrm{C}\), the rms speed of the molecules will be :

Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2nd Balmer line (n = 4 to n = 2) will be :

Following figure shows two processes A and B for a gas. If \(\Delta Q_A\) and \(\Delta Q_B\) are the amount of heat absorbed by the system in two cases, and \(\Delta U_A\) and \(\Delta U_B\) are changes in internal energies, respectively, then :

The electric field in a region is given by \(\vec{E} = (Ax + B)\hat{i}\), where \(E\) is in \(\mathrm{NC^{-1}}\) and \(x\) is in metres. The values of constants are \(A = 20\) SI unit and \(B = 10\) SI unit. If the potential at \(x = 1\) is \(V_1\) and that at \(x = -5\) is \(V_2\), then \(V_1 - V_2\) is :-

A damped harmonic oscillator has a frequency of 5 oscillations per second. The amplitude drops to half its value for every 10 oscillations. The time it will take to drop to \(1/1000\) of the original amplitude is close to :-

Let \(\left|\vec{A_1}\right| = 3\), \(\left|\vec{A_2}\right| = 5\) and \(\left|\vec{A_1} + \vec{A_2}\right| = 5\). The value of \(\left(2\vec{A_1} + 3\vec{A_2}\right)\cdot\left(3\vec{A_1} - 2\vec{A_2}\right)\) is :-

A circuit connected to an ac source of emf \(e = e_0\sin(100t)\) with \(t\) in seconds, gives a phase difference of \(\pi/4\) between the emf \(e\) and current \(i\). Which of the following circuits will exhibit this ?