NEET 2017 Physics

A Carnot engine having an efficiency of 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 :

The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m, is:

Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that 8^th bright fringe in the medium lies where 5^th dark fringe lies in air. The refractive index of the medium is nearly:

The diagrams below show regions of equipotentials.

A positive charge is moved from A to b in each diagram.

A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N?

A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves:

The two nearest harmonics of a tube closed at one end and open at other end are 220Hz and 260Hz. What is the fundamental frequency of the system ?

Two cars moving in opposite directions approach each other with speed of 22 m/s and 16.5 m/s respectively. The driver of the first car blows a horn having a frequency 400 Hz. The frequency heard by the driver of the second car is [velocity of sound 340 m/s]:

A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be:

Consider a drop of rain water having mass 1g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take ‘g’ constant with a value 10 m/s². The work done by the (i) gravitational force the (ii) resistive force of airs is:

The ratio of resolving powers of an optical microscope for two wavelengths λ₁ = 4000 A˚ and λ₂ = 6000 A˚ is:

A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system:

Which of the following statements are correct?
(a) Centre of mass of a body always coincides with the centre of gravity of the body.
(b) Centre of mass of a body is the point at which the total gravitational torque on the body is zero.
(c) A couple on a body produce both translational and rotational motion in a body.
(d) Mechanical advantage greater than one means that small effort can be used to lift a large load.

A thin prism having refracting angle 10^o is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be :

Which one of the following represents forward bias diode?

A longer solenoid of diameter 0.1m has 2×10⁴ turns per meter. At the center of the solenoid, a coil of 100 turns and radius 0.01m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0A from 4A in 0.05s. If the resistance of the coil is 10π²Ω, the total charge flowing through the coil during this time is:

The given electrical network is equivalent to:

In an electromagnetic wave in free space the root mean square value of the electric filed is E_rms = 6V/m. The peak value of the magnetic field is:

Thermodynamic process are indicated in the following diagram.

Match the following:

The x and y coordinates of the particle at any time are x = 5t − 2t² and y = 10t respectively, where x and y are in meters and t in seconds. The acceleration of the particle at t = 2s is:

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is:

A spring of force constant k is cut into lengths of ratio 1:2:3 They are connected in series and the new force constant is k′. Then they are connected in parallel and force constant is k″. Then k′ : k″ is:

Two astronauts are floating in gravitational free space after having lost contact with their spaceship. The two will.

A 250-Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 μA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180° against the torque is:

An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current ‘I’ along the same direction is shown in Fig. Magnitude of force per unit length on the middle wire ‘B’ is given by:

In a common emitter transistor amplifier the audio signal voltage across the collector is 3 V. The resistance of collector is 3 kΩ. If current gain is 100 and the base resistance is 2 kΩ, the voltage and power gain of the amplifier is :

A physical quantity of the dimensions of length that can be formed out of c, G and (e² / 4πε₀) is [c is velocity of light, G is universal constant of gravitation and e is charge]:

A gas mixture consists of 2 moles of O₂ and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is

Suppose the charge of a proton and an electron differ slightly. One of them is -e, the other is (e+Δe). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then Δe is of the order of [Given mass of hydrogen mh = 1.67 × 10⁻²⁷Kg]

Figure shows a circuit that contains three identical resistors with resistance R = 9.0 Ω each, two identical inductors with inductance L = 2.0 mH each, and an ideal battery with emf ε = 18 V. The current, ‘i’ through the battery just after the switch closed is

Two discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities ω₁ and ω₂. They are brought into contact face to face coinciding the axis of rotation. The expression for loss coinciding of energy during this process is:

If θ₁ and θ₂ be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip θ is given by

A particle executes linear simple harmonic motion with an amplitude of 3 cm. When the particular is at 2 cm from the mean position, the magnitude of its velocity is equal to that its acceleration. Then its time period in seconds is:

The bulk modulus of a spherical objects is ‘B‘. If it is subjected to uniform pressure ‘p‘, the fractional decrease in radius is:

The photoelectric threshold wavelength of silver is 3250 x 10⁻¹⁰m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 x 10⁻¹⁰m is:
(Given h = 4.14 × 10⁻¹⁵ eVs and c = 3 x 10⁸m/s)

Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivity are K₁ and K₂. The thermal conductivity of the composite rod will be :

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t₁. On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time t₂. The time taken by her walk up on the moving escalator will be:

One end of string of length l is connected to a particle of mass ‘m’ and the other end is connected to a small peg on a smooth horizontal table. If the particle moves in circle with speed ‘v’, the net force on the particle (directed towards center) will be (T represents the tension in the string)

A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by:

The resistance if a wire is ‘R’ ohm. If it is melted and stretched to ‘n’ times its original length, its new resistance will be:

Radioactive material ‘A’ has decay constant ‘8λ’ and material ‘B’ has decay constant ‘λ’. Initially they have same number of nuclei of material ‘B’ to that ‘A’ will be 1/e?

Two Polaroids P₁ and P₂ are placed with their axis perpendicular to each other. Unpolarised light I₀ is incident on P₁. A third polaroid P3 is kept in between P₁ and P₂ such that its axis makes an angle 45° with that of P₁. The intensity of transmitted light through P₂ is:

A U tube with both end open to the atmosphere is partially filled with water, Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10 mm above the water level on the other side. Meanwhile, the water rises by 65 mm from its original level (see diagram). The density of the oil is:

Two blocks A and B of masses 3 m and m respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively: