Recent questions tagged 2012

Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is

asked Aug 20, 2018 by pady_1

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An $\alpha$-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 $\frac{Wb}{m^2}$ . The de-Broglie wavelength associated with the particle will be

asked Aug 20, 2018 by pady_1

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When a biconves lens of glass having refractive index 1.47 is dipped in a liqud, it acts as a plane sheet of glass. This implies that the liquid must have refractive index.

asked Aug 20, 2018 by pady_1

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A concave mirror of focal length $'f_1'$ is placeed at a distance of 'd' from a convex lens of focal length $'f_2'$ A beam of light coming from infinity and falling on this convex lens- concave mirror combination returns to infinity. The dsitance 'd' must equal

asked Aug 20, 2018 by pady_1

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A ray of light is incident at an angle of incidence, i, on one face of a prism of angle A (assumed to be small) and emerges normally from the opposite face. It the refractive index of the prism is$\mu$, the angle of incidence i, is nearly equal to

asked Aug 20, 2018 by pady_1

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The magnifying power of a teloscope is 9. When it is adjusted for parallel rays the distance between the objective and eyepiece is 20 cm. The focal length of lenses are

asked Aug 20, 2018 by pady_1

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An alternating electric field, of frequency v, is applied across the dees (radius = R) of a cyclotron that is being used to accelerated protons (mass = m). The operating magnetic field (B) used in the cyclotron and the kinetic energy (K) of the proton beam, produced by it, are given by

asked Aug 20, 2018 by pady_1

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Two similar coils of radius R are lying concentrically with their planes at right angles to each other.The currents flowing in them are I and 2I, respectively. The resultant magnetic field induction at the centre will be

asked Aug 20, 2018 by pady_1

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A milli voltmeter of 25 milli volt range is to be converted into an ammeter of 25 ampere rage. The value (in ohm) of necessary shunt will be

asked Aug 20, 2018 by pady_1

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A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It.

asked Aug 20, 2018 by pady_1

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Four point charge –Q, –q, 2q and 2Q are placed, one at each corner of the square. The relation between Q and q for which the potential at the centre of the square is zero is

asked Aug 20, 2018 by pady_1

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An electric dipole of moment 'p' is placed in an electric field of intensity 'E'. The dipole acquires a position such that the axis of the dipole makes an angle $\theta$ with the direction of the field.Assuming that the potential energy of the dipole to be zero when $\theta = 90º$, the torque and the potential energy of thedipole will respectively be

asked Aug 20, 2018 by pady_1

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What is the flux through a cube of side 'a' if a point charge of q is at one of its corner.

asked Aug 20, 2018 by pady_1

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The electric field associated with an e. m. wave in vacuum is given by $\overrightarrow{E}=\hat{i}40 cos(KZ-6\times10^8t)$,where E, z and t are in ${volt}{m}$, meter and seconds respectively. The value of wave vector k is :

asked Aug 20, 2018 by pady_1

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In the circuit shown the cells A and B have negligible resistance. For $V_A = 12V, R_1 = 500\Omega and R =100 \Omega$ the galvanometer (G) shows no deflection. The value of $V_B$ is

asked Aug 20, 2018 by pady_1

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If voltage across a bulb rated 220 Volts.- 100 Watt drops by 2.5% of its rated value the percentage of the rated value by which the power would decrease is

asked Aug 20, 2018 by pady_1

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A ring is made of a wire having a resistance $R_0 = 12\Omega$ . Find the points A and B, as shown in the figure, at which a current carrying conductor should be connected so that the resistance R of the sub circuit between these points is equal to $\frac{8}{3}\Omega$ : <br>

asked Aug 20, 2018 by pady_1

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In an electrical circuit R, L, C and an a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the ciruit is $\frac{\pi}{3}$ . If instead, C is removed from the circuit, the phase difference is again $\frac{\pi}{3}$ . The power factor of the circuit is

asked Aug 20, 2018 by pady_1

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The current (I) in the inductance is varying with time according to the plot shown in figure. Which one of the following is the correct variation of voltage with time in the coil ? <br>

asked Aug 20, 2018 by pady_1

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A coil of resistance $400\Omega$ is placed in a magnetic filed. if the magnetic flux $\phi$ (wb) linked with the coil varies with times t(sec) as <br> $\phi = 50 t^2 + 4.$ . The current is the coil at t = 2 sec is

asked Aug 20, 2018 by pady_1

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If the radius of a star is R and it acts as a black body, what would be the temperature of the star, in which the rate of energy production is Q ?

asked Aug 20, 2018 by pady_1

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Liquid oxygen at 50 K is heated to 300 K at constant pressure of 1 atm. The rate of heating is constant. Which one of the following graphs represents the variation of temperature with time ?

asked Aug 20, 2018 by pady_1

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A thermodynamics system is taken trough the cycle ABCD as shown in figure. Heat rejected by the gas during the cycle is : <br>

asked Aug 20, 2018 by pady_1

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One mole of an ideal gas goes from an initial state A to final state B via two processes : It firs undergoes isothermal expansion from volume V to 3V and then its volume is reduced from 3toVat constant pressure. The correct P-V diagram representing the two processes is:

asked Aug 20, 2018 by pady_1

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When a string is divided into three segments of length $l_1,\; l_2 \;and\; l_3$, the fundamental frequencies of these three segments are $v_1, \;v_2 \;and \;v_3$ respectively. The original functamental frequency (v) of the string is :

asked Aug 20, 2018 by pady_1

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Two sources of sound placed close to each other, are emitting progressive waves given by $y_1 = 4 sin 600 \pi t $ and $y_2 = 5 sin 608 \pi t$

asked Aug 20, 2018 by pady_1

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The height at which the weight of a body becomes $\frac{1}{16}$th , its weight on the surface of earth (radius R), is

asked Aug 20, 2018 by pady_1

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A geostationary satellite is orbiting the earth at a height of 5R above that surface of the earth, R being the radius of the earth. The time period of another satellite of the earth. The time period of another satellite in hours at a height of 2R from the surface of the earth is

asked Aug 20, 2018 by pady_1

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A spherical planet has a mass $M_P$ and diameter $D_P$. A particle of mass m falling freely near the surface of this planet will experience an acceleration due to gravity, equal to

asked Aug 20, 2018 by pady_1

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When a mass is rotating in a plane about a fixed point, its angular momentum is directed along

asked Aug 20, 2018 by pady_1

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ABC is an equilateral triangle with O as its centre $\overrightarrow{F_1},\overrightarrow{F_2} and \overrightarrow{F_3}$ represent three forces acting along the sides AB, BC and AC respectively. If the torque about O is zero then the magnitude of $\overrightarrow{F_3}$ is

asked Aug 20, 2018 by pady_1

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Two persons of masses 55 kg and 65kg respectively, are at the opposite ends of a boat. The length of the boat is 30. m and weighs 100 kg. The 55 kg man walks up to the 65 kg man and sits with him. If the boat is in still water the center of mass of the system shift by:

asked Aug 20, 2018 by pady_1

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Two spheres A and B of masses m1 and m2 respectively collide. A is at rest initially and B is moving with velocity v along x-axis. After collision B has a velocity$\frac{v}{2}$ in a direction perpendicular to the original direction. The mass A moves after collision in the direction.

asked Aug 20, 2018 by pady_1

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The potential energy of a particle in a force field is :$U=\frac{A}{r^2}-\frac{B}{r}$ where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is

asked Aug 20, 2018 by pady_1

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A solid cylinder of mass 3 kg is rolling on a horizontal surface with velocity $4 ms^{–1}$. It collides with a horizontal spring of force constant $200 Nm^{–1}$ . The maximum compression produced in the spring will be

asked Aug 20, 2018 by pady_1

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A car of mass $1000\; kg$ negotiates a banked curve of radius $90\;m$ on a frictionless road. If the banking angle is $45^{\circ}$, the speed of the car is

asked Aug 20, 2018 by pady_1

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A particle has initial velocity $\bigg( 2\overrightarrow{i}+3 \overrightarrow{j}\bigg)$ and acceleration $\bigg( 0.3\overrightarrow{i}+0.2 \overrightarrow{j}\bigg)$ .The magnitude of velocity after 10 seconds will be

asked Aug 20, 2018 by pady_1

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The horizontal range and the maximum height of a projectile are equal . The angle of projection of the projectile is:

asked Aug 20, 2018 by pady_1

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The motion of a particle along a straight line is described by equation $x = 8 + 12t –t^3$ where x is in metre and t in second. The retardation of the particle when its velocity becomes zero is

asked Aug 20, 2018 by pady_1

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