List of top Physics Questions asked in JEE Main

The temperature of equal masses of three different liquids x, y and z are 10\(^{\circ}\)C, 20\(^{\circ}\)C and 30\(^{\circ}\)C respectively. The temperature of mixture when x is mixed with y is 16\(^{\circ}\)C and that when y is mixed with z is 26\(^{\circ}\)C. The temperature of mixture when x and z are mixed will be :

Two blocks of masses 3 kg and 5 kg are connected by a metal wire going over a smooth pulley. The breaking stress of the metal is \( \frac{24}{\pi} \times 10^2 \) Nm\(^{-2}\). What is the minimum radius of the wire ? 
(take g=10 ms\(^{-2}\)) 

 

A refrigerator consumes an average 35 W power to operate between temperature -10\(^{\circ}\)C to 25\(^{\circ}\)C. If there is no loss of energy then how much average heat per second does it transfer ?

In the given circuit the AC source has \(\omega\) = 100 rad s\(^{-1}\). Considering the inductor and capacitor to be ideal, what will be the current I flowing through the circuit ? 

A cylindrical container of volume 4.0\( \times \)10\(^{-3}\) m\(^3\) contains one mole of hydrogen and two moles of carbon dioxide. Assume the temperature of the mixture is 400 K. The pressure of the mixture of gases is :
[Take gas constant as 8.3 J mol\(^{-1}\)K\(^{-1}\)]
An electric bulb of 500 watt at 100 volt is used in a circuit having a 200 V supply. Calculate the resistance R to be connected in series with the bulb so that the power delivered by the bulb is 500 W.

A parallel-plate capacitor with plate area A has separation d between the plates. Two dielectric slabs of dielectric constant K\(_1\) and K\(_2\) of same area A/2 and thickness d/2 are inserted in the space between the plates. The capacitance of the capacitor will be given by: 

 

If you are provided a set of resistances 2 \( \Omega \), 4 \( \Omega \), 6 \( \Omega \) and 8 \( \Omega \). Connect these resistances so as to obtain an equivalent resistance of \( \frac{46}{3} \Omega \).
The two thin coaxial rings, each of radius 'a' and having charges +Q and -Q respectively are separated by a distance of 's'. The potential difference between the centres of the two rings is:

For the given circuit, the power across zener diode is __________ mW. 

 

The acceleration due to gravity is found upto an accuracy of 4% on a planet. The energy supplied to a simple pendulum of known mass 'm' to undertake oscillations of time period T is being estimated. If time period is measured to an accuracy of 3%, the accuracy to which E is known as __________ %.
Two simple harmonic motions are represented by the equations \( x_1 = 5 \sin(2\pi t + \frac{\pi}{4}) \) and \( x_2 = 5\sqrt{2}(\sin(2\pi t) + \cos(2\pi t)) \). The amplitude of second motion is __________ times the amplitude in first motion.
If the maximum value of accelerating potential provided by a radio frequency oscillator is 12 kV. The number of revolution made by a proton in a cyclotron to achieve one sixth of the speed of light is __________.
[m\(_p\) = 1.67\( \times \)10\(^{-27}\) kg, e = 1.6\( \times \)10\(^{-19}\) C, Speed of light = 3\( \times \)10\(^8\) m/s]
A source of light is placed in front of a screen. Intensity of light on the screen is I. Two Polaroids P\(_1\) and P\(_2\) are so placed in between the source of light and screen that the intensity of light on screen is I/2. P\(_2\) should be rotated by an angle of __________ (degrees) so that the intensity of light on the screen becomes \(\frac{3I}{8}\).

An object is placed at a distance of 12 cm from a convex lens. A convex mirror of focal length 15 cm is placed on other side of lens at 8 cm as shown in the figure. Image of object coincides with the object. When the convex mirror is removed, a real and inverted image is formed at a position. The distance of the image from the object will be __________ (cm). 

 

A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad s\(^{-1}\) in a uniform horizontal magnetic field of 3.0\( \times \)10\(^{-2}\) T. The maximum emf induced the coil will be __________ \( \times \)10\(^{-2}\) volt (rounded off to the nearest integer).
A coil in the shape of an equilateral triangle of side 10 cm lies in a vertical plane between the pole pieces of permanent magnet producing a horizontal magnetic field 20 mT. The torque acting on the coil when a current of 0.2 A is passed through it and its plane becomes parallel to the magnetic field will be \( \sqrt{x} \times 10^{-5} \) Nm. The value of x is __________.
Two waves are simultaneously passing through a string and their equations are :
\(y_1 = A_1 \sin k(x - vt), y_2 = A_2 \sin k(x-vt+x_0)\). Given amplitudes \(A_1 = 12\) mm and \(A_2 = 5\) mm, \(x_0=3.5\) cm and wave number \(k=6.28\) cm\(^{-1}\). The amplitude of resulting wave will be __________ mm.
In a Screw Gauge, fifth division of the circular scale coincides with the reference line when the ratchet is closed. There are 50 divisions on the circular scale, and the main scale moves by 0.5 mm on a complete rotation. For a particular observation the reading on the main scale is 5 mm and the 20th division of the circular scale coincides with reference line. Calculate the true reading.
The rms speeds of the molecules of Hydrogen, Oxygen and Carbondioxide at the same temperature are $V_H$, $V_O$ and $V_C$ respectively then :

Identify the logic operation carried out by the given circuit : 

A particular hydrogen like ion emits radiation of frequency $2.92 \times 10^{15}$ Hz when it makes transition from n=3 to n=1. The frequency in Hz of radiation emitted in transition from n=2 to n=1 will be :
Two narrow bores of diameter 5.0 mm and 8.0 mm are joined together to form a U-shaped tube open at both ends. If this U-tube contains water, what is the difference in the level of two limbs of the tube. [Take surface tension of water $T = 7.3 \times 10^{-2}$ $Nm^{-1}$, angle of contact $= 0$, $g = 10$ $ms^{-2}$ and density of water $= 1.0 \times 10^3$ kg $m^{-3}$]
In a photoelectric experiment ultraviolet light of wavelength 280 nm is used with lithium cathode having work function $\phi = 2.5$ eV. If the wavelength of incident light is switched to 400 nm, find out the change in the stopping potential. ($h=6.63 \times 10^{-34}$ Js, $c=3 \times 10^8$ $ms^{-1}$)
Car B overtakes another car A at a relative speed of 40 $ms^{-1$. How fast will the image of car B appear to move in the mirror of focal length 10 cm fitted in car A, when the car B is 1.9 m away from the car A ?}