JEE Main 2020 January 8 Shift 2 Question Paper & Solutions - JEE MCQ

An object is gradually moving away from the focal point of a concave mirror along the axis of the mirror. The graphical representation of the magnitude of linear magnification (m) versus distance of the object from the mirror (x) is correctly given by:
(Graphs are drawn schematically and are not to scale)

A transverse wave travels on a taut steel wire with a velocity of v when tension in it is 2.06 × 10⁴ N. When the tension is changed to T, the velocity changed to v/2. The value of T is close to

A galvanometer having a coil resistance 100 Ω gives a full scale deflection when a current of 1 mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of 10 V?

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

As shown in the figure, a battery of emf E is connected to an inductor L and resistance R in series. The switch is closed at t = 0. The total charge that flows from the battery, between t = 0 and t = t_C (tC is the time constant of the circuit) is:

Two liquids of densities are filled up behind a square wall of side 10 m as shown in figure. Each liquid has a height of 5 m. The ratio of the forces due to these liquids exerted on upper part MN to that at the lower part NO is: (Assume that the liquids are not mixing)

A particle of mass m is dropped from a height h above the ground. At the same time, another particle of the same mass is thrown vertically upwards from the ground with a speed of . If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of , is

A simple pendulum is being used to determine the value of gravitational acceleration g at a certain place. The length of the pendulum is 25.0 cm and a stopwatch with 1 s resolution measures the time taken for 40 oscillation to be 50 s. The accuracy in g is

A particle of mass m and charge q is released from rest in a uniform electric field. If there is no other force on the particle, the dependence of its speed v on the distance x travelled by it is correctly given by: (Graphs are schematic and not drawn to scale.)

A capacitor is made of two square plates each of side 'a' making a very small angle α between them, as shown in figure. The capacitance will be close to

Consider two charged metallic spheres S₁ and S₂ of radii R₁ and R₂, respectively. The electric fields E₁ (on S₁) and E₂ (on S₂) on their surfaces are such that E₁/E₂ = R₁/R₂. Then the ratio V₁(on S₁)/V₂(on S₂) of the electrostatic potentials on each sphere is

A plane electromagnetic wave of frequency 25 GHz is propagating in vacuum along the z-direction. At a particular point in space and time, the magnetic field is given by . The corresponding electric field  is: (Speed of light, c = 3 × 108 ms^-1)

In a double-slit experiment, at a certain point on the screen, the path difference between the two interfering waves is 1/8th of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is

A very long wire ABDMNDC is shown in figure carrying current I. AB and BC parts are straight, long and at right angles. At D, wire forms a circular turn DMND of radius R. AB, BC parts are tangential to circular turn at N and D. Magnetic field at the centre of circle is

As shown in fig., when a spherical cavity (centred at O) of radius 1 is cut out of a uniform sphere of radius R (centred at C), the centre of mass of remaining (shaded) part of sphere is at G, i.e. on the surface of the cavity. R can be determined by the equation:

A particle moves such that its position vector r(t) = cos ωt i + sin ωt j, where ω is a constant and t is time. Then which of the following statements is true for the velocity vector v(t) and acceleration vector a(t) of the particle?

An electron (mass m) with initial velocity  is in an electric field . If  is initial de Broglie wavelength of electron, its de Broglie wavelength at time t is given by

Three containers C₁, C₂ and C₃ have water at different temperatures. The table below shows the final temperature T when different amounts of water (given in litres) are taken from each container and mixed (assume no loss of heat during the process).

The value of θ (in °C, to the nearest integer) is _______.

An asteroid is moving directly towards the centre of the earth. When at a distance of 10 R (R is the radius of the earth) from the earth's centre, it has a speed of 12 km/s. Neglecting the effect of earth's atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is 11.2 km/s)? Give your answer to the nearest integer in kilometres/s.

The series combination of two batteries, both of the same emf 10 V but different internal resistances of 20 Ω and 5Ω , is connected to the parallel combination of two resistors 30Ω  and R Ω. The voltage difference across the battery of internal resistance 20Ω  is zero, the value of R (in Ω) is _______.

The first member of the Balmer series of hydrogen atom has a wavelength of 6561 . The wavelength of the second member of the Balmer series (in nm) is _______.
(Answer up to the nearest integer)

A ball is dropped from the top of a 100 m high tower on a planet. In the last 1/2s before hitting the ground, it covers a distance of 19 m. Acceleration due to gravity (in ms^–2) near the surface on that planet is _______.(Nearest Integer)

Among the compounds A and B with molecular formula C₉H₁₈O₃, A is having a higher boiling point than B. The possible structures of A and B are:

Which of the following compounds is likely to show both Frenkel and Schottky defects in its crystalline form?

Among the reactions (a) - (d), the reaction(s) that does/do not occur in the blast furnace during the extraction of iron is/are:
(a) CaO + SiO₂ → CaSiO₃
(b) 3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂
(c) FeO + SiO₂ → FeSiO3
(d) 

The increasing order of the atomic radii of the following elements is:
(a) C
(b) O
(c) F
(d) CI
(e) Br

The radius of the second Bohr orbit, in terms of the Bohr radius a0, in Li²⁺ is: