List of top Physics Questions asked in JEE Main

In an experiment to determine the velocity of sound in air at room temperature using a resonance tube, the first resonance is observed when the air column has a length of 20.0 cm for a tuning fork of frequency 400 Hz is used. The velocity of the sound at room temperature is 336 ms–1. The third resonance is observed when the air column has a length of ______ cm.
The vernier constant of Vernier callipers is 0.1 mm and it has zero error of (–0.05) cm. While measuring diameter of a sphere, the main scale reading is 1.7 cm and coinciding vernier division is 5. The corrected diameter will be ________× 10–2 cm.
The half life of a radioactive substance is 5 years. After x years, a given sample of the radioactive substance gets reduced to 6.25% of its initial value. The value of x is ______.
An npn transistor with current gain \(β = 100\) in common emitter configuration is shown in the figure. The output voltage of the amplifier will be
npn transistor with current gain

A potential barrier of 0.4 V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 × 105 ms–1. The speed with which electrons enters the p side will be
\(\frac{x}{3} × 10^5\) ms-1
the value of x is _________.
(Give mass of electron = 9 × 10–31 kg, charge on electron = 1.6 × 10–19 C)

A vessel contains 16 g of hydrogen and 128 g of oxygen at standard temperature and pressure. The volume of the vessel in cm3 is:

In a carnot engine, the temperature of reservoir is 527°C and that of sink is 200 K. If the work done by the engine when it transfers heat from reservoir to sink is 12000 kJ, the quantity of heat absorbed by the engine from reservoir is _____ \(× 10^6\) J.

An inductor of 0.5 mH, a capacitor of 200 μF and a resistor of 2 Ω are connected in series with a 220 V ac source. If the current is in phase with the emf, the frequency of ac source will be ______ × 102 Hz

In the given figure, the block of mass m is dropped from the point ‘A’. The expression for kinetic energy of block when it reaches point ‘B’ is

Fig. 
In a double slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the plane of slits. If the screen is moved by 5 × 10–2 m towards the slits, the change in fringe width is 3 × 10–3 cm. If the distance between the slits is 1 mm, then the wavelength of the light will be _______ nm.
If the electric potential at any point (x, y, z)m in space is given by V = 3x2 volt. The electric field at the point (1, 0, 3)m will be
A FM Broad cast transmitter, using modulating signal of frequency 20 kHz has a deviation ratio of 10. The Bandwidth required for transmission is
The motion of a simple pendulum executing S.H.M. is represented by the following equation. y = A sin(πt + φ), where time is measured in second. The length of pendulum is

Two resistors are connected in series across a battery as shown in figure. If a voltmeter of resistance 2000 Ω is used to measure the potential difference across 500 Ω resistor, the reading of the voltmeter will be _____ V.

Fig. Resistors
A person can throw a ball upto a maximum range of 100 m. How high above the ground he can throw the same ball?
A small spherical ball of radius 0.1 mm and density 104 kg m–3 falls freely under gravity through a distance h before entering a tank of water. If, after entering the water the velocity of ball does not change and it continue to fall with same constant velocity inside water, then the value of h will be ______ m.
(Given g = 10 ms–2, viscosity of water = 1.0 × 10–5 N-sm–2).

The moment of inertia of a uniform thin rod about a perpendicular axis passing through one end is I1. The same rod is bent into a ring and its moment of inertia about a diameter is I2. If
\(\frac{I_1}{I_2}\) is \(\frac{xπ²}{3}\)
then the value of x will be ______.

The power of a lens (biconvex) is \(1.25 m^{–1}\) in particular medium. Refractive index of the lens is \(1.5\), and the radii of curvature are \(20 cm\) and \(40 cm\), respectively. The refractive index of surrounding medium
In young’s double slit experiment the two slits are 0.6 mm distance apart. Interference pattern is observed on a screen at a distance 80 cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be _____ nm.
According to kinetic theory of gases,
A. The motion of the gas molecules freezes at 0°C
B. The mean free path of gas molecules decreases if the density of molecules is increased.
C. The mean free path of gas molecules increases if temperature is increased keeping pressure constant.
D. Average kinetic energy per molecule per degree of freedom is \(\frac{3}{2}k_BT\) (for monoatomic gases).
Choose the most appropriate answer from the options given below:
The height of a transmitting antenna at the top of a tower is 25 m and that of receiving antenna is, 49 m. The maximum distance between them, for satisfactory communication in LOS (Line-Of-Sight) is \(K\sqrt5\times10^2\ m\). The value of K is ______ .
(Assume radius of Earth is \(64×10^5\ m\))
[Calculate upto nearest integer value]
A beam of monochromatic light is used to excite the electron in \(Li^{++}\) from the first orbit to the third orbit. The wavelength of monochromatic light is found to be \(x × 10^{–10}\) m. The value of \(x\) is _____ .[Given \(hc = 1242\) eV nm]
If L, C and R are the self-inductance, capacitance and resistance, respectively, which of the following does not have the dimension of time?
A convex lens has power P. It is cut into two halves along its principal axis. Further one piece (out of the two halves) is cut into two halves perpendicular to the principal axis . Choose the incorrect option for the reported pieces.
The SI unit of a physical quantity is pascal-second. The dimensional formula of this quantity will be