NEET 2015 Physics

A certain metallic surface is illuminated with monochromatic light of wavelength λ. The stopping potential for photoelectric current for this light is 3V₀. If the same surface is illuminated with light of wavelength 2λ, the stopping potential is V₀. The threshold wavelength for this surface for photoelectric effect is

A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?

A potentiometer wire has length 4m resistance 8Ω. The resistance that must be connected in series with the wire and an accumulator of emf 2V, so as to get a potential gradient of 1 mV per cm on the wire is

A radiation of energy ‘E’ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c= velocity of light)

A resistance R draws power P when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes Z the power drawn will be

A wire carrying current I has the shape as shown in adjoining figure. Linear parts of the wire are very long and parallel to X-axis while semicircular portion of radius R is lying in yz-plane. Magnetic field at point O is

A,B and C are voltmeters of resistance R, 1.5 R and 3R respectively, as shown in the figure. When some potential difference is applied between X and Y, then the voltmeter readings are VA,VB and VC, respectively. Then,

Across a metallic conductor of non-uniform cross-section, a constant potential difference is applied. The quantity which remain (s) constant along the conductor is

An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude

Consider 3rd orbit of He⁺(helium), using non-relativistic approach, the speed of electron in this orbit will be (given K = 9 × 10⁹ constant, Z = 2 and h = 6.6 × 10⁻³⁴ J-s)

For a parallel beam of monochromatic light of wavelength λ diffraction is produced by a single slit whose width a is of the order of the wavelength of the light. If D is the distance of the screen from the slit, the width of the central maxima will be

If radius of the ₁₃Al²⁷ nucleus is taken to be Rᴀı, then the radius of ₅₃Te¹²⁵ nucleus is nearly

In a double slit experiment, the two slits are 1 mm apart and the screen is placed 1 m away. A monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double slit within the central maxima of single slit pattern?

The refracting angle of a prism is A and refractive index of the material of the prism is cot (A/2). The angle of minimum deviation is

Two identical thin plano-convex glass lenses (refractive index 1.5) each having radius of curvature of 20 cm are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index 1.7. The focal length of the combination is

Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?

If energy(E), velocity(V) and time(T) are chosen as fundamental quantities, the dimensional formula of surface tension will be

A particle of unit mass undergoes one-dimensional motion such that its velocity varies according to v(x) = bx⁻²ⁿ, where b and n are constants and x is the position of the particle. The acceleration of the particle as d function of x is given by

A ship A is moving westwards with a speed of 10 km/h and a ship B 100 km South of A is moving Northwards with a speed of 10 km/h. The time after which the distance between them becomes shortest is

A block of mass m₁ rests on a horizontal table. A light string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m₂ is suspended. The coefficient of kinetic friction between the block and the table is μ. When the block A is sliding on the table, the tension in the string is

Three blocks A,B and C of masses 4 kg, 2 kg and 1 kg respectively are in contact on a frictionless surface as shown in fig. If a force of 14 N is applied on the 4 kg block, the the contact force between A and B is

A block of mass 10 kg, moving in x direction with a constant sped of 10 ms⁻¹, is subject to a retarding force F = 0.1 x J/m during its travel from x=20 m to 30 m. Its final KE will be

Two similar springs P and Q have spring constants Kᴘ and Kǫ, such that Kᴘ > Kǫ. They are stretched, first by the same amount (case a,) then by the same force (case b). The work done by the springs Wᴘ and Wǫ are related as, in case (a) and case (b), respectively

A particle of mass m is driven by a machine that delivers a constant power of k watts. If the particle starts from rest the force on the particle at time t is

A mass m moves in a circle on a smooth horizontal plane with velocity v₀ at a radius R₀. The mass is attached to string which passes through a smooth hole in the plane as shown.

The tension in the string is increased gradually and finally m moves in a circle of radius R₀/2. The final value of the kinetic energy is

A rod of weight W is supported by two parallel knife edges A and B is in equilibrium in a horizontal position. The knives are at a distance d from each other. The centre of mass of the rod is at distance x from A. The normal reaction on A is

Three identical spherical shells, each of mass m and radius r are placed as shown in figure. Consider an axis XX’ which is touching to two shells and passing through diameter of third shell. Moment of inertia of the system consisting of these three spherical shells about XX’ axis is

Kepler’s third law states that square of period of revolution (T) of a planet around the sun, is proportional to third power of average distance r between sun and planet i.e. T²=Kr³ here K is constant. If the masses of sun and planet are M and m respectively then as per Newton’s law of gravitation force of attraction between them is F = GMm/r², here G is gravitational constant. The relation between G and K is described as

Two spherical bodies of mass M and 5 M and radii R and 2 R released in free space with initial separation between their centres equal to 12 R. If they attract each other due to gravitational force only, then the distance covered by the smaller body before collision is

The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 x 10⁻¹¹ Pa⁻¹ and density of water is 10³ kg/m³. What fractional compression of water will be obtained at the bottom of the ocean?

A wind with speed 40 m/s blows parallel to the roof of a house. The area of the roof is 250 m². Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be (ρair=1.2 kg/m³)

On observing light from three different stars P, Q and R, it was found that intensity of violet colour is maximum in the spectrum of P, the intensity of green colour is maximum in the spectrum of R and the intensity of red colour is maximum in the spectrum of Q. If Tp,TQ and TR are the respective absolute temperature of P,Q and R, then it can be concluded from the above observations that

The two ends of a metal rod are maintained at temperatures 100°C and 110°C. The rate of heat flow in the rod is found to be 4.0 J/s. If the ends are maintained at temperatures 200°C and 210°C, the rate of heat flow will be

A Carnot engine, having an efficiency of η = 1/10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

Figure below shows two paths that may be taken by a gas to go from a state A to a state C. In process AB, 400 J of heat is added to the system and in process BC, 100 J of heat is added to the system. The heat absorbed by the system in the process AC will be

One mole of an ideal diatomic gas undergoes a transition from A to B along a path AB as shown in the figure.

The change in internal energy of the gas during the transition is

The ratio of specific heats Cp/Cv = γ in terms of degrees of freedom (n) is given by

When two displacements represented by y₁ = a sin(ωt) are superimposed the motion is

A particle is executing SHM along a straight line. Its velocities at distances x₁ and x₂ from the mean position are V₁ and V₂ respectively. Its time period is

The fundamental frequency of a closed organ pipe of length 20 cm is equal to the second overtone of an organ pipe open at both the ends. The length of organ pipe open at both the ends is

The electric field in a certain region is acting radially outward and is given by E=Ar. A change contained in a sphere of radius ‘a’ centred at the origin of the field, will be given by

A conducting square frame of side ‘a’ and a long straight wire carrying current I are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity ‘V’. The emf induced in the frame will be proportional to

Two particles of masses m₁,m₂ move with initial velocities u₁ and u₂. On collision, one of the particles get excited to higher level, after absorbing energy ?. If final velocities of particles be v₁ and v₂ then we must have

Which logic gate is represented by the following combination of logic gate?

If in a p-n junction, a square input signal of 10 V is applied as shown, then the output across Rʟ will be