NEET 2021 Physics Questions

In the product $\vec F=q\,\vec v\times\vec B$, for $q=1$, $\vec v=2\hat i+4\hat j+6\hat k$ and $\vec F=4\hat i-20\hat j+12\hat k$, the complete expression for $\vec B$ is:

A car starts from rest and accelerates at $5\ \mathrm{m/s^2}$. At $t=4$ s a ball is dropped out of a window by a person sitting in the car. What are the velocity and acceleration of the ball at $t=6$ s? (Take $g=10\ \mathrm{m/s^2}$)

A particle moving in a circle of radius $R$ with uniform speed takes a time $T$ to complete one revolution. If this particle is projected with the same speed at an angle $\theta$ to the horizontal, the maximum height attained equals $4R$. The angle of projection $\theta$ is given by:

A screw gauge gives the following readings when used to measure the diameter of a wire: Main scale reading: 0 mm; Circular scale reading: 52 divisions. Given that 1 mm on the main scale corresponds to 100 divisions on the circular scale, the diameter of the wire is:

If force [F], acceleration [A] and time [T] are chosen as the fundamental physical quantities, find the dimensions of energy.

If E and G respectively denote energy and gravitational constant, then E/G has the dimensions of:

The escape velocity from the earth's surface is v. The escape velocity from the surface of another planet of radius four times that of earth and the same mean density is:

A particle is released from rest at height S above the earth's surface. At a certain height its kinetic energy is three times its potential energy (taking the surface as reference). The height above the surface and the speed at that instant are respectively:

A particle of mass m is projected with velocity u = k·vₑ (k < 1) from the earth's surface (vₑ = escape velocity). The maximum height above the surface reached by the particle is:

From a circular ring of mass M and radius R, an arc corresponding to a 90° sector is removed. The moment of inertia of the remaining part about an axis through the centre and perpendicular to the plane is K·MR². Then K is:

A uniform rod (200 cm, 500 g) is balanced on a wedge at the 40 cm mark. A 2 kg mass hangs at the 20 cm mark and an unknown mass m hangs at the 160 cm mark. For equilibrium, m is: (g = 10 m/s²)

Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g=10 m/s²)

A particle is released from height S from the surface of the Earth. At a certain height its kinetic energy is three times its potential energy. The height from the surface of the Earth and the speed of the particle at that instant are respectively

A body executes simple harmonic motion with frequency n. The frequency of variation of its potential energy is

A spring is stretched by 5 cm under a force of 10 N. The time period of oscillation when a mass of 2 kg is suspended from it is

A small block slides down from the top of a smooth inclined plane starting from rest at t = 0. If $S_n$ is the distance travelled by it from t = (n-1) s to t = n s, the ratio $\dfrac{S_n}{S_{n+1}}$ is:

A ball of mass 0.15 kg is dropped from a height of 10 m, strikes the ground and rebounds to the same height. The magnitude of the impulse imparted to the ball is nearly (g = 10 m/s²):

Match Column-I with Column-II and choose the correct match from the given choices: Column-I (A) Root mean square speed of gas molecules (B) Pressure exerted by ideal gas (C) Average kinetic energy of a molecule (D) Total internal energy of 1 mole of a diatomic gas Column-II (i) ⅓ n m v²_rms (ii) √(3RT/M) (iii) (5/2) RT (iv) (3/2) k_B T Choose the correct match:

A cup of coffee cools from 90 °C to 80 °C in t minutes when the room temperature is 20 °C. The time taken by a similar cup of coffee to cool from 80 °C to 60 °C at the same room temperature (20 °C) is:

The velocity of a small ball of mass M and density d, when dropped in a container filled with glycerine, becomes constant after some time. If the density of glycerine is d/2, then the viscous force acting on the ball will be:

A parallel plate capacitor has a uniform electric field 'E' in the space between the plates. If the distance between the plates is 'd' and the area of each plate is 'A' the energy stored in the capacitor is: (ε₀ = permittivity of free space)

Two charged spherical conductors of radius R1 and R2 are connected by a wire. Then the ratio of surface charge densities of the sphere (sigma1/sigma2) is:

A dipole is placed in an electric field as shown. In which direction will it move?

Twenty seven drops of same size are charged at 220 V each. They combine to form a bigger drop. Calculate the potential of the bigger drop.

Polar molecules are the molecules:

The equivalent capacitance of the combination shown in the figure is:

The effective resistance of four identical wires in parallel is 0.25 $\Omega$. Their effective resistance in series is:

In a potentiometer, a cell of emf 1.5 V balances at 36 cm. If a 2.5 V cell replaces it, the balance length is:

Three resistors r$_{1}$, r$_{2}$, r$_{3}$ are connected as shown. The ratio i$_{3}$/i$_{1}$ of currents in terms of the resistances is:

The electron concentration in an n-type semiconductor equals the hole concentration in a p-type. An electric field is applied across each. Compare the currents:

Match Column-I with Column-II: Column-I (A) Drift velocity (B) Electrical resistivity (C) Relaxation period (D) Current density Column-II (P) $m/(ne^{2}\rho)$ (Q) $ne\cdot v_d$ (R) $(eE/m)\tau$ (S) $E/J$ Choose the correct match:

In the product F = q(v × B) = q(v_x î + v_y ĵ + v_z k̂) × (B_x î + B_y ĵ + B_z k̂), for q = 1 and v = 2î + 4ĵ + 6k̂ and F = 4î − 20ĵ + 12k̂, what will be the complete expression for B?

A thick current cable of radius R carries current 'I' uniformly distributed across its cross-section. The variation of magnetic field B(r) due to the cable with the distance 'r' from the axis of the cable is represented by:

An infinitely long straight conductor carries a current of 5 A as shown. An electron is moving with a speed of 10⁵ m/s parallel to the conductor. The perpendicular distance between the electron and the conductor is 20 cm at an instant. Calculate the magnitude of the force experienced by the electron at the instant.

A uniform conducting wire of length 12a and resistance 'R' is wound up as a current carrying coil in the shape of (i) an equilateral triangle of side 'a'. (ii) a square of side 'a'. The magnetic dipole moments of the coil in each case respectively are:

A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since

A convex lens 'A' of focal length 20 cm and a concave lens 'B' of focal length 5 cm are kept along the same axis with a distance 'd' between them. If a parallel beam of light falling on 'A' leaves 'B' as a parallel beam, then the distance 'd' in cm will be

Find the value of the angle of emergence from the prism shown in the figure. The refractive index of the glass is √3 and the ray strikes the exit face of the prism at an internal angle of 30° to the normal.

A point object is placed at a distance of 60 cm from a convex lens of focal length 30 cm. If a plane mirror were put perpendicular to the principal axis of the lens and at a distance of 40 cm from it, the final image would be formed at a distance of

For the given circuit, the input digital signals are applied at the terminals A, B and C. What would be the output waveform at the terminal Y?

Consider the following Statements (A) and (B) and identify the correct answer. A. A zener diode is connected in reverse bias when used as a voltage regulator. B. The potential barrier of a p-n junction lies between 0.1 V to 0.3 V.

The electron concentration in an n-type semiconductor is the same as the hole concentration in a p-type semiconductor. An external electric field is applied across each of them. Compare the currents in them.

Two charged spherical conductors of radii R₁ and R₂ are connected by a wire. Then the ratio of the surface charge densities of the spheres (σ₁/σ₂) is

Polar molecules are the molecules:

A dipole is placed in a non-uniform electric field as shown. In which direction will it move?

A series LCR circuit containing 5.0 H inductor, 80 μF capacitor and 40 Ω resistor is connected to 230 V variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the power at the resonant angular frequency are likely to be:

An inductor of inductance L, a capacitor of capacitance C and a resistor of resistance 'R' are connected in series to an ac source of potential difference 'V' volts as shown in figures. Potential difference across L, C and R is 40 V, 10 V and 40 V, respectively. The amplitude of current flowing through LCR series circuit is 10√2. The impedance of the circuit is :

A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?

A capacitor of capacitance C is connected across an ac source of voltage V given by V = V₀ sin ωt. The displacement current between the plates of the capacitor would then be given by

For a plane electromagnetic wave propagating in the +x-direction, which one of the following combinations gives a correct possible pair of directions for the electric field (E) and magnetic field (B) respectively?

The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600 nm, when it delivers the power of 3.3 × 10⁻³ W will be: (h = 6.6 × 10⁻³⁴ J·s)

An electromagnetic wave of wavelength λ is incident on a photosensitive surface of negligible work function. If a photoelectron of mass m emitted from the surface has de Broglie wavelength λ_d, then:

Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 >> R2, the mutual inductance M between them will be directly proportional to: