NEET 2018 Physics Questions

A moving block of mass m collides with a stationary block of mass 4m. The lighter block comes to rest after the collision. If the initial velocity of the lighter block is v, the coefficient of restitution (e) is:

A block of mass m is placed on a smooth inclined wedge ABC of inclination θ. The wedge is given a horizontal acceleration 'a' towards the right. The relation between a and θ for the block to remain stationary on the wedge is:

A body, initially at rest, slides down a frictionless track from a height h (as shown) and just completes a vertical circle of diameter AB = D. The height h is equal to:

Which one of the following statements is incorrect?

The moment of the force F = 4î + 5ĵ + 6k̂ acting at the point (2, 0, -3), about the point (2, -2, -2), is:

A solid sphere rotates freely about its symmetry axis in free space. Its radius is increased keeping the mass constant. Which quantity stays constant?

Three bodies A (solid sphere), B (disc), C (ring), each of mass M and radius R, spin about their symmetry axes with the same angular speed. The work needed to stop them satisfies:

The volume ($V$) of a monatomic gas varies with its temperature ($T$), as shown in the graph (a straight line through the origin, from A to B, i.e. an isobaric process). The ratio of the work done by the gas to the heat absorbed by it, when it goes from A to B, is

The efficiency of an ideal heat engine working between the freezing point and boiling point of water is

$0.1$ g of water at $100\,^\circ$C and normal pressure ($1.013\times 10^{5}$ N/m$^2$) requires $54$ cal to convert into steam at $100\,^\circ$C. If the volume of the steam produced is $167.1$ cc, the change in internal energy is

A body initially at rest, sliding along a frictionless track from a height h, just completes a vertical circle of diameter AB=D. The height h is equal to

A moving block of mass m collides with another stationary block of mass 4m. The lighter block comes to rest after the collision. When the initial velocity of the lighter block is v, the value of the coefficient of restitution (e) is

A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If the screw gauge has a zero error of -0.004 cm, the correct diameter of the ball is:

Which one of the following statements is incorrect?

The fundamental frequency of an open organ pipe equals the third harmonic of a closed organ pipe. If the length of the closed pipe is 20 cm, the length of the open pipe is:

A tuning fork produces resonance in a glass tube whose air-column length is varied by a piston. At 27 °C, two successive resonances occur at column lengths 20 cm and 73 cm. If the tuning fork frequency is 320 Hz, the speed of sound in air at 27 °C is:

If the mass of the Sun were ten times smaller and the universal gravitational constant G ten times larger, which statement is NOT correct?

The kinetic energies of a planet in an elliptical orbit about the Sun at positions A, B and C are K_A, K_B and K_C. AC is the major axis and SB ⊥ AC at the Sun S (see figure). Then:

A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field E. Due to the force qE, its velocity increases from 0 to 6 m/s in one second duration. At that instant the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively:

The moment of the force $\vec F=4\hat i+5\hat j+6\hat k$ acting at the point $(2,0,-3)$, about the point $(2,-2,-2)$, is given by:

At what temperature will the rms speed of oxygen molecules become just sufficient for escaping from the Earth's atmosphere? (Given: mass of an oxygen molecule m = 2.76 × 10⁻²⁶ kg, Boltzmann constant k_B = 1.38 × 10⁻²³ J K⁻¹, escape speed = 11200 ms⁻¹)

Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by Δl on applying a force F, how much force is needed to stretch the second wire by the same amount?

A pendulum hung from the roof of a tall building moves freely to and fro as a simple harmonic oscillator. The acceleration of the bob is 20 m/s² at a distance of 5 m from the mean position. The time period of oscillation is

The power radiated by a black body is P and it radiates maximum energy at wavelength λ₀. If the temperature is changed so that it now radiates maximum energy at wavelength (3/4)λ₀, the power radiated becomes nP. The value of n is:

A small sphere of radius 'r' falls from rest in a viscous liquid. As a result, heat is produced due to the viscous force. The rate of production of heat, when the sphere attains its terminal velocity, is proportional to:

The refractive index of the material of a prism is √2 and the angle of the prism is 30°. One of the two refracting surfaces of the prism is made a mirror inwards by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is

An astronomical refracting telescope will have large angular magnification and high angular resolution when it has an objective lens of

An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be

A carbon resistor of (47 ± 4.7) k$\Omega$ is to be marked with rings of different colours for its identification. The colour code sequence will be:

A set of 'n' equal resistors (R each) in series with a battery (emf E, internal resistance R) draws current I. In parallel they draw 10I. The value of n is:

A battery of n identical cells (each internal resistance r) in series is short-circuited and the current I measured. Which graph shows I vs n?

In a p-n junction diode, change in temperature due to heating:

In the combination of the following gates, the output Y can be written in terms of inputs A and B as:

Unpolarised light is incident from air on a plane surface of a material of refractive index μ. At a particular angle of incidence i, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?

In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength λ of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same λ and D) the separation between the slits needs to be changed to

A metallic rod of mass per unit length 0.5 kg m⁻¹ is lying horizontally on a smooth inclined plane which makes an angle of 30° with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is:

Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is:

An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf V = 10 sin 340 t. The power loss in A.C. circuit is :

An inductor 20 mH, a capacitor 100 μF and a resistor 50 Ω are connected in series across a source of emf, V = 10 sin 314 t. The power loss in the circuit is

When the light of frequency 2ν₀ (where ν₀ is the threshold frequency) is incident on a metal plate, the maximum velocity of electrons emitted is v₁. When the frequency of the incident radiation is increased to 5ν₀, the maximum velocity of electrons emitted from the same plate is v₂. The ratio of v₁ to v₂ is:

An electron of mass m with an initial velocity v = v₀ î (v₀ > 0) enters an electric field E = −E₀ î (E₀ = constant > 0) at t = 0. If λ₀ is its de Broglie wavelength initially, then its de Broglie wavelength at time t is:

The electrostatic force between the metal plates of an isolated parallel plate capacitor C having a charge Q and area A, is

The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom is:

An EM wave is propagating in a medium with velocity V = V î (along +x). The instantaneous oscillating electric field of this EM wave is along the +y axis. Then the direction of the oscillating magnetic field of the EM wave will be along

A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current is switched on, the diamagnetic rod is pushed up, out of the horizontal magnetic field, gaining gravitational potential energy. The work required to do this comes from:

The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance