JEE Main entrance exam Question Bank Solutions for Physics (JEE Main)

The mobility of electrons in a semiconductor chip of length 10 cm is observed to be 1000 cm²/Vs. When a potential difference of vis applied across it. What is the drift speed of electrons.

Four identical particles of mass M are located at the corners of a square of side 'a'. What should be their speed if each of them revolves under the influence of the other's gravitational field in a circular orbit circumscribing the square?

The number of molecules in 1 cm³ of an ideal gas at 0°C and at a pressure of 10^-5 mm of mercury is ______.

In a p-type semiconductor the acceptor level is situated 57 meV above the valence band. The maximum wavelength of light required to produce a hole will be: 

The bob of a simple pendulum has a mass of 2g and a charge of 5.0 µC. It is at rest in a uniform horizontal electric field of intensity 2000 V/m. At equilibrium, the angle that the pendulum makes with the vertical is ______.

(take g = 10 m/s²)

An object is 20 cm away from a concave mirror and it is within the focal length of the mirror. If the mirror is changed to a plane mirror, the image moves 15 cm closer to the mirror.

Focal length of the concave mirror is ______.

In the given circuit, initially switch S₁ is closed and S₂ and S₃ are open. After charging of capacitor, at t = 0, S₁ is open and S₂ and S₃ are closed. If the relation between inductance capacitance and resistance is L = 4CR² then the time (in sec) after which current passing through capacitor and inductor will be same is ______ × 10^-4 N. (Given R = ℓn(2)_mΩ, L = 2mH)

At NTP the density of a gas is 1.3 kw/m³ and the velocity of sound propagation in the gas is 330 m/s. The degree of freedom of gas molecule is ______.

Parallel rays striking a spherical mirror far from the optic axis are focussed at a different point than are rays near the axis thereby the focus moves toward the mirror as the parallel rays move toward the outer edge of the mirror. What value of incidence angle θ produces a 2% change in the location of the focus, compared to the location for θ very close to zero?

Which of the following quantities is zero on an average for the molecules of an ideal gas in equilibrium?

A current I = 10 sin(100π t) A is passed in first coil, which induces a maximum e.m.f of 5π volt in second coil. The mutual inductance between the coils is ______.

A triatomic molecule can be modelled as three rigid sphere joined by three rigid rods forming an triangle. Consider a triatomic gas consisting such molecule. If gas performs 30 J work when it expands under constant pressure the heat given to gas is ______.

A particle is dropped along the axis from a height 15 cm on a concave mirror of focal length 30 cm as shown in figure. The acceleration due to gravity is 10 m/s². Find the maximum speed of image in m/s:

What is the electric potential needed to excite He⁺ to its first excited state?

One solenoid is centered inside another. The outer one has a length of 50.0 cm and contains 6750 coils, while the coaxial inner solenoid is 3.0 cm long and π cm² in area and contains 150 coils. The current in the outer solenoid is changing at 3000 A/s. The emf induced in the inner solenoid is ______ V.

(Round off to two decimal places.)

A particle of mass 5 × 10^-5 kg is placed at the lowest point of a smooth parabola having the equation 20x² = y (x, y in m). Here y is the vertical height. If it is displaced slightly and is constrained to move along the parabola, the angular frequency (in rad/s) of small oscillations is ______.

If the lattice parameter for a crystalline structure is 3.6 Å, then the atomic radius in fcc crystal in Å is ______.

If the potential barrier across a p-n junction is 0.6 V. Then the electric field intensity, in the depletion region having the width of 6 × 10^-6m, will be ______ × 10⁵ N/C.

The wavelength of the K_α line is ______ Pm in copper (Z = 29) if the wavelength of the K_α = line in iron (Z = 26) is known to be equal to 193 picometers.

The position of the centre of mass of a uniform semi-circular wire of radius 'R' placed in x-y plane with its centre at the origin and the line joining its ends as x-axis is given by `(0, (xR)/pi)`. Then, the value of |x| is ______.