Recent questions in JEEMAIN PAST PAPERS

In the circuit, the galvanometer $G$ shows zero deflection. If the batteries $A$ and $B$ have negligible internal resistance, the value of the resistor $R$ will be:

asked Nov 5, 2018 by pady_1

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Two voltameters, one of copper and another of silver, are joined in parallel. When a total charge $q$ flows through the voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are $z_1$ and $z_2$ respectively, the charge which flows through the silver voltameter is :

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A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 V, the resistance in Ohm's needed to be connected in series with the coil will be :

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A nuclear transformation is denoted by $X(n, \alpha) \to ^7_3 Li$ . Which of the following is the nucleus of element $X$ ?

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In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be :

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In a common base amplifer, the phase difference between the input signal voltage and output voltage is :

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If the kinetic energy of a free electron doubles, its de-Broglie wavelength changes by the factor :

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The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy ?

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A thin glass (refractive index 1.5) lens has optical power of -5 D in air. Its optical power in a liquid medium with refractive index 1.6 will be :

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Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately, what is the maximum distance at which these dots can be resolved by the eye ? [Take wavelength of light = 500 nm]

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A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is 12 cm below the water surface, the radius of this circle in cm is :

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Two simple harmonic motions are represented by the equations $y_1 = 0.1 \sin (100 \pi t + \frac{\pi}{3} )$ and $y_2 = 0.1 \cos \pi t$ . The phase difference of the velocity of particle 1, with respect to the velocity of particle 2 is :

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A Young's double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is :

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The function $\sin^2( \omega t)$ represents :

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A system goes from A to B via two process I and II as shown in figure. If $\Delta U_1$ and $\Delta U_2$ are the changes in internal energies in the process I and II respectively, then :

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The figure shows a system of two concentric spheres of radii $r_1$ and $r_2$ and kept at temperature $T_1$ and $T_2$ , respectively. The radical rate of flow of heat in a substance between the two concentric spheres, is proportional to :

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The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is :

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If radius of the $^{27}_{13} Al$ nucleus is estimated to be 3.6 fermi, then the radius of $^{125}_{52} Te$ nucleus be nearly :

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Starting with a sample of pure $^{66}Cu, 7/8$ of it decays into Zn in 15 min. The corresponding half life is :

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A Photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed $\frac{1}{2}m$ away, the number of electrons emitted by photocahode would :

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The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm, is incident on it. The band gap in (eV) for the semiconductor is :

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The intensity of gamma radiation from a given source is $I$ . On passing through 36 mm of lead, it is reduced to $\frac{I}{8}$ . The thickness of lead, which will reduce the intensity to $\frac{I}{2}$ will be :

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A gaseous mixture consists of 16 g of helium and 16 g of oxygen. The ratio $\frac{C_p}{C_{\nu}}$ of the mixture is :

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A particle of mass 10 g is kept on the surface of a uniform sphere of mass 100 kg and radius 10 cm. Find the work to be done against the gravitational force between them, to take the particle far away from the sphere : (you may take $G=6.67 \times 10^{-11}\; Nm^2/kg^2$ )

asked Nov 5, 2018 by pady_1

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The change in the value of $g$ at a height $h$ above the surface of the earth is the same as at a depth $d$ below the surface of earth. When both $d$ and $h$ are much smaller than the radius of earth, then which one of the following is correct ?

asked Nov 5, 2018 by pady_1

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A $T$ shaped object with dimensions shown in figure, is lying on a smooth floor. A force $\overrightarrow{F}$ is applied at the point $P$ parallel to $AB$ , such that the object has only the translational motion without rotation. Find the location of $P$ with respect to $C$ :

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Which of the following is incorrect regarding the first law of thermodynamics ?

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Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped , is : $[\mu_k = 0.5]$

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A body of mass m is accelerated uniform from rest to a speed $\nu$ in a time $T$ . The instantaneous power delivered to the body as a function of time, is given by :

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Average density of the earth :

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If $S$ is stress and $Y$ is Young's modulus of material of a wire, the energy stored in the wire per unit volume is :

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A 20 cm long capillary tube is dipped in water. The water rises upto 8 cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be :

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A mass m moves with a velocity $\nu$ and collides inelastically with another identical mass. After collision the $I^{st}$ mass moves with velocity $\frac{\nu}{\sqrt{3}}$ in a direction perpendicular to the initial direction of motion. Find the speed of the second mass after collision :

asked Nov 5, 2018 by pady_1

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The block of mass M moving on the frictionless horizontal surface collides with the spring of spring constant $k$ and compresses it by length $L$ . The maximum momentum of the block after collision is :

asked Nov 5, 2018 by pady_1

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A particle of mass $0.3 \;kg$ is subjected to a force $F = -kx$ with $k = 15\; N/m$ . What will be its initial acceleration, if it is released from a point 20 cm away from the origin ?

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The moment of inertia of uniform semicircular disc of mass M and radius r about a line perpendicular to the plane of the disc through the centre is :

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A body A of mass M while falling vertically downwards under gravity breaks into two parts; a body B of mass $\frac{1}{3} M$ and, a body C of mass $\frac{2}{3}M$ . The centre of mass of body B and C taken together shifts compared to that of body A towards :

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A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It rolls down a smooth surface to the ground, then climbs up another hill of height 30 m and finally rolls down to a horizontal base at a height of 20 m above the ground. The velocity attained by the ball is :

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A block is kept on a frictionless inclined surface with angle of inclination $\propto$ . The incline is given an acceleration $a$ to keep the block stationary. Then $a$ is equal to :

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A parachutist after bailing out falls 50 m without friction. When parachute opens, it decelerates at $2\;m/s^2$ . he reaches the ground with a speed of $3 \; m/s$ . At what height, did he bail out ?

asked Nov 5, 2018 by pady_1

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A particle is moving eastwards with a velocity of $5\; ms^{-1}$ . In $10 \;s$ the velocity changes to $5\;ms^{-1}$ northwardas. The average acceleration in this time is:

asked Nov 5, 2018 by pady_1

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A car starting from rest, accelerates at the rate $f$ through a distance $S$ , then continues at constant speed for time $t$ and then decelerates at the rate $f/2$ to come to rest. If the total distance travelled is $15 \;S$ , then :

asked Nov 5, 2018 by pady_1

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The relation between time $t$ and distance $x$ is $t=ax^2+bx$ , where $a$ and $b$ are constants. The acceleration is :

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Out of the following pairs, which one does not have identical dimensions ?

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A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. How much further it will penetrate before coming to rest, assuming that it faces constant resistance to motion ?

asked Nov 5, 2018 by pady_1

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The upper half of an inclined plane with inclination $\phi$ is perfectly smooth, while the lower half is rough. A body starting from rest at the top will again come to rest at the bottom, if the coefficient of friction for the lower half is given by :

asked Nov 5, 2018 by pady_1

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A smooth block is released at rest on a $45^{\circ}$ incline and then slides a distance $d$ . The time taken to slide is $n$ times as much to slide on rough inclined than on a smooth incline. The coefficient of friction is :

asked Nov 5, 2018 by pady_1

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An annular ring with inner and outer radii $R_1$ and $R_2$ is rolling without slipping with a uniform angular seed. The ratio of the forces experienced by the two particles situated on the inner and outer parts of the ring, $\frac{F_1}{F_2}$ is :

asked Nov 5, 2018 by pady_1

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A projectile can have the same range R for two angles of projection. If $t_1$ and $t_2$ be the times of flights in the two cases, then the product of the two times of flights is proportional to :

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When p-n junction diode is forward biased

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