Recent questions in 2017

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 :

asked Oct 31, 2017 by meena.p

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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 po35:r radiated in watt would be

asked Oct 31, 2017 by meena.p

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Consider a drop of rain water having mass 1 g falling from a height of 1km. It hits the ground with a speed of 50 m/s. Take 'g' constant with a value $10 m/s^2$ . The work done by the (i) gravitational force and the (ii) resistive force of air is:

asked Oct 31, 2017 by meena.p

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The ratio of resolving powers of an optical microscope for two wavelengths $\lambda_1=4000 A$ and $\lambda_2 =6000 A$ is:

asked Oct 31, 2017 by meena.p

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The bulk modulus of a sphericaI object is B. lf it is subjected to , uniform pressure 'p' , the fractional decrease in radius is

asked Oct 27, 2017 by meena.p

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In an electromagnetic wave in free space the root mean square value of the electric field is $E_{rms} = 6V/m.$ The peak value of the magnetic field is:

asked Oct 27, 2017 by meena.p

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

asked Oct 27, 2017 by meena.p

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

asked Oct 27, 2017 by meena.p

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If $\theta_1$ and $\theta_2$, be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip 0 is given by :

asked Oct 27, 2017 by meena.p

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A carnot engine having an efficiency of $\large\frac{1}{10}$ as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energv absorbed from the reservoir at lower temperature is :

asked Oct 27, 2017 by meena.p

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Which of the following statements are correct ?

asked Oct 26, 2017 by meena.p

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The acceleration due to gravity at a height I km above the earth is the same as at a depth d below the , surface of earth. Then :

asked Oct 26, 2017 by meena.p

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The given electricaI network is equivalent to

asked Oct 25, 2017 by meena.p

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A spring of force constant k is cut into lengths of ratio $I : 2 :3$ . They are connected in series and the, new force constant is 'K'.- Then they are connected is parallel and force constant is k". Then k, : k, is

asked Oct 25, 2017 by meena.p

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Which one of the following represents; forward bias diode?

asked Oct 11, 2017 by meena.p

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In a common emitter transistor amplifier the audio signal voltage across the collector is $3 \Omega$. If current gain is 100 and the base resistance is $2 k \Omega$ , the voltage and power gain of the amplifier is :

asked Oct 11, 2017 by meena.p

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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]

asked Oct 10, 2017 by meena.p

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A physical quantity of the dimensions of length that can be formed out of c, G and $\large\frac{e^2}{4 \pi \in_0}$ is [c is velocity of light, G is universal constant of gravitation and e is charge ] :

asked Oct 10, 2017 by meena.p

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The photo electric threshold wave length of silver is $3250 \times 10^{-10}\;m$ . The velocity of the electrons ejected from a silver surface by ultraviolet light of wavelength $2536 \times 10^{-10}\;m$ is : (Given $h=4.14 \times 10^{-10} \;eVs$ and $c= 3 \times 10^{8} \;ms^{-1})$

asked Oct 10, 2017 by meena.p

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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 :

asked Oct 10, 2017 by meena.p

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Thermodynamic processes are indicated in the following diagram.

asked Oct 10, 2017 by meena.p

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

asked Oct 10, 2017 by meena.p

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

asked Oct 10, 2017 by meena.p

0 answers

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

asked Oct 10, 2017 by meena.p

1 answer

Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are $K_1$ and $K_2$. The thermal conductivity of the composite rod will be

asked Oct 10, 2017 by meena.p

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Suppose the charge of a proton and an eleckon differ slightly. One of them is - e, the other is $(e + \Delta e)$. 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 $\Delta_e$ is of the order of [Given mass of hydrogen $m_h= 1.67 \times 10^{27}\;kg]$

asked Oct 7, 2017 by meena.p

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The x and y coordinates of the particle at any time are $x= 5t - 2t^2$ and $y = 10t$ respectivelv, where r and y are in meters and t in seconds. The acceleration of the particle at $t = 2s$ is

asked Oct 7, 2017 by meena.p

1 answer

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

asked Oct 7, 2017 by meena.p

1 answer

One end of string of length I is connected to a particle of mass 'nf and the other end is connected to a small peg on a smooth horizontal table. If the particle moves in circle with speed 'u', the net force on the particle (directed towards center) will be ([ represents the tension in the string)

asked Oct 7, 2017 by meena.p

0 answers

The de - Brogile wave length of a neutron in thermal equilibrium with heavy water at a temperature T and mass m , is

asked Oct 7, 2017 by meena.p

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A 250 N turn rectangular coil of length $2.1\;cm$ and width $1.25\;cm$ carries a current of $85 \mu A$ and subjected to magnetic field of strength $0.85\;T$ Work done for rotating the coil by $180^{\circ}$ against the torque is :

asked Oct 7, 2017 by meena.p

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A U tube with both ends open to the atmosphere, is partially filled rvith u,ater. Oil, which is imeriscible with water, is poured into one side until itstands at a distance of 10 mtrr 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 :

asked Oct 7, 2017 by meena.p

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Radioactive material 'A' has decay constant $8 \lambda$ and material 'B' has decay constant $\lambda$. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be $\large\frac{1}{e} $?

asked Oct 7, 2017 by meena.p

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A gas mixture consists of 2 moles of O, and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the totalintemal energv of l.he system is :

asked Oct 7, 2017 by meena.p

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

asked Oct 7, 2017 by meena.p

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