Recent questions tagged 2000

Which of the following reacts with ethanol to form chloroform ?

asked Dec 19, 2018 by pady_1

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The focal length of the lenses of an astronomical telescope are 50 cm and 5 cm. The length of the telescope when the image is formed at the least distance of distinct vision is :

asked Dec 19, 2018 by pady_1

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A source producing sound of frequency $170 \; Hz$ is approaching a stationary observer with a velocity of $17\;ms^{-1}$. The apparent change in the wavelength of sound heard by the observer is : (speed of sound in air = $340\; ms^{-1}$)

asked Dec 19, 2018 by pady_1

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If vibrating tuning fork of frequency $255 \;Hz$ is moving wih a velocity $4\;ms^{-1}$ towards the wall the number of beat heard per second is (speed of sound in air = $340\;ms^{-1}$) :

asked Dec 19, 2018 by pady_1

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The frequency of a stretched uniform wire under tension is in resonance with the fundamental frequency of a closed tube. If the tension in the wire is increased by 8 N, it is in resonance with the first over-tone of the closed tube. The initial tension in the wire is :

asked Dec 19, 2018 by pady_1

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Two metal rods A and B of equal lengths and equal cross-sectional areas are joined end to end. The coefficients of thermal conductivities of A and B are in the ratio 2:3, when the free end of A is maintained at $100^{\circ}C$ and the free end of B is maintained at $0^{\circ}C$, the temperature of the junction is :

asked Dec 19, 2018 by pady_1

1 answer

The liquids at temperature $60^{\circ}C$ and $30^{\circ}C$ respectively have masses in the ratio $3:4$ and their specific heats in the ratio $4:5$. If the two liquids are mixed, the resultant temperature is :

asked Dec 19, 2018 by pady_1

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An ideal gas at a pressure of $1\;atm$ and temperature of $27^{\circ}C$ is compressed adiabatically until its pressure becomes 8 times the initial pressure , then final temperature is :$ (\gamma = 3/2)$

asked Dec 19, 2018 by pady_1

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A flask is filled with $1.3\;g$ of an ideal gas at $27^{\circ}C$ and its temperature is raised to $52^{\circ}C$. The mass of the gas that has to be released to maintain the temperature of the released to maintain the temperature of the gas in the flask at $52^{\circ}C$ and the pressure remaining the same is :

asked Dec 19, 2018 by pady_1

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A vessel is filled with an ideal gas at a pressure of $10$ atmosphere and temperature $27^{\circ}C$. Half of the mass of the gas is removed from the vessel and temperature of the remaining gas is increased to $87^{\circ}C$. Then the pressure of the gas in the vessel will be :

asked Dec 19, 2018 by pady_1

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When a liquid in a glass vessel, is heated its apparent expansion is $10.30 \times 10^{-4}/^{\circ}C$ same liquid when heated in a metal its apparent expansion $10.06 \times 10^{-4}/^{\circ}C$. The coefficient of linear expansion of the metal is : (coefficient of linear expansion of glass = $9 \times 10^{-6}/^{\circ}C$) :

asked Dec 19, 2018 by pady_1

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8000 identical water drops are combined to form a big drop. The the ratio of final surface energy to the initial surface energy of all the drops together is :

asked Dec 19, 2018 by pady_1

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When a uniform wire of radius $r$, is stretched by a $2\;kg$ weight the increase in its length is $2.00\; mm$ If the radius of the wire is $\frac{r}{2}$ and other conditions remining the same, the increase in its length is :

asked Dec 19, 2018 by pady_1

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A particle executing simple harmonic motion has an amplitude of $6\;cm$. Its acceleration at a distance from the mean position $2\;cm$ is $8\;cm/sec^2$. The maximum speed of the particle is :

asked Dec 19, 2018 by pady_1

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A body of mass $1 \; kg$ is executing simple harmonic motion. Its displacement $y\;cm$ at $t\;sec$ is given by $y = 6 \sin (100 t + \frac{\pi}{4})$ its maximum kinetic energy is :

asked Dec 19, 2018 by pady_1

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The height of the point vertically above the earth's surface at which acceleration due to gravity becomes 1% of its value at the surface is : (Radius of the earth = R)

asked Dec 19, 2018 by pady_1

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$R$ and $r$ are the radii of the earth and moon respectively, $\rho_e$ and $\rho_m$ are densities of earth and moon respectively . The ratio of the acceleration due to gravity on the surfaces of the moon and earth, is :

asked Dec 19, 2018 by pady_1

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A wheel has a speed of $1200$ revolution per minute and is made to slow down at a rate of $4\; radian/sec^2$. The number of revolutions it makes before coming to rest is :

asked Dec 19, 2018 by pady_1

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The radius of gyration of a sphere of mass $M$ and radius $R$ about the axis parallel to the axis passing through its centre and tangent to the sphere is :

asked Dec 19, 2018 by pady_1

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A body is sliding down an inclined plane having coefficient of friction 0.5. If the normal reaction is twice that of the resultant downward force along the incline the angle between the inclined plane and the horizontal is :

asked Dec 19, 2018 by pady_1

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A 1.0 HP motor pumps out water from a well of 30 m and fills a water tank of volume 2238 litres at a height of 10 m from the ground. The running time of the motor to fill the empty water tank is :

asked Dec 19, 2018 by pady_1

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A ball is projected vertically down with an initial velocity from a height of 20 m on to a horizontal floor. During the impact it losses 50% of the energy and rebounds to the same height, the initial velocity of its projection is :

asked Dec 19, 2018 by pady_1

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A body of mass $m_1$ moving with a velocity $10\;ms^{-1}$ collides with another body at rest of mass $m_2$. After collision the velocities of the two bodies are $2\;ms^{-1}$ and $5 \; ms^{-1}$ respectively, along the direction of motion of $m_1$. The ratio $\frac{m_1}{m_2}$ is :

asked Dec 19, 2018 by pady_1

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A force of $5N$ making an angle $\theta$ with the horizontal acting on an object displaces it by $0.4\;m$ along the horizontal direction. If the object gains kinetic energy of $1\;J$ the horizontal component of the force is :

asked Dec 19, 2018 by pady_1

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Four bodies $P, \; Q, \; R$ and $S$ are projected with equal velocities having angles of projection $15^{\circ}, \; 30^{\circ}, \; 45^{\circ}$ and $60^{\circ}$ with the horizontal respectively. The body having shortest range is :

asked Dec 19, 2018 by pady_1

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A body is thrown horizontally from the top of a tower of 5 m height. It touches the ground at a distance of 10 m from the foot of the tower. The initial velocity of the body is:

asked Dec 19, 2018 by pady_1

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A body is thrown vertically upwards with an initial velocity $u$ reaches maximum height in $6\;sec$. The ratio of distance travelled by the body in the first and seventh second is :

asked Dec 19, 2018 by pady_1

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The displacement $r$ of a charge $Q$ in an electric field $\overrightarrow{E} = c_1 \hat{i} + c_2 \hat{j} + c_3 \hat{k}$ is $\overrightarrow{r} = a \hat{i} + b \hat{j}$. The work done is :

asked Dec 19, 2018 by pady_1

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If pressure $P$, velocity $v$ and time $T$ are taken as fundamental physical quantities the dimensional formula of the force is :

asked Dec 19, 2018 by pady_1

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The fundamental physical quantities that have same dimensions in the dimensional formula of torque and angular momentum are :

asked Dec 19, 2018 by pady_1

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Consider the following statements A and B and identify the correct choice of the given answers : (A) The width of the depletion layer in a $p-n$ junction diode increases in forward bias. (B) In a intrinsic semiconductor the fermi energy level in exactly in the middle of the forbidden energy gap.

asked Dec 19, 2018 by pady_1

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To generate power of $3.2\; MW$, the number of fissions $U^{235}$ per minute is : (Energy released per fission = $200\; MeV, \; 1eV =1.6 \times 10^{-19} J $)

asked Dec 19, 2018 by pady_1

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In Bohr model of hydrogen atom, the ratio of period of revolutionn of an electron in $n=2$ and $n=1$ orbit is :

asked Dec 19, 2018 by pady_1

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The ratio of the longest and shortest wave-lengths in Bracket series of hydrogen spectra is :

asked Dec 19, 2018 by pady_1

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The energy of an X-ray photon of wavelength $1.65 \mathring{A}$ is : ($h = 6.6 \times 10^{-34} Js, \; c = 3 \times 10^8 ms^{-1}, \; 1eV = 1.6 \times 10^{-19}J$)

asked Dec 19, 2018 by pady_1

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When a metal surface is illuminated by a light of wavelength $400\;nm$ and $250\; nm$. The maximum velocities of the photo electrons ejected are $v$ and $2v$ respectively. The work function of the metal is : (h = Planck's constant, c = velocity of light in air )

asked Dec 19, 2018 by pady_1

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The $X$-ray wavelength of $L_a$ line of platinum $(Z = 78)$ is $1.30 \mathring{A}$. The $X$-ray wavelenght of $L_a$ line of molybdenum $(Z =42)$ is :

asked Dec 19, 2018 by pady_1

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Two wires of equal diameters of resistivities $\rho_1$ and $\rho_2$ and lengths $x_1$ and $x_2$ respectively are joined in series. The equivalent resistivity of the combination is :

asked Dec 19, 2018 by pady_1

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Two electric charges $12 \mu C$ and $-6 \mu C$ are placed $20\;cm$ apart in air, there will be a point $P$ at which electric potential is zero on the line joining these two charges and out side excluding the region between them. The distance of $P$ from $-6 \mu C$ charge is :

asked Dec 19, 2018 by pady_1

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An ammeter and a voltmeter of resistance $R$ are connected in series to an electric cell of negligible internal resistance. Their readings are A and V respectively. If another resistance $R$ is connected in parallel with voltmeter :

asked Dec 19, 2018 by pady_1

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In a compound microscope cross wires are fixed at the point :

asked Dec 19, 2018 by pady_1

1 answer

Consider the following statements A and B and identify the correct choice in the given answers : (A) Line spectra is due to atoms in gaseous state. (B) Band spectra is due to molecules

asked Dec 19, 2018 by pady_1

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Under minimum deviation condition in a prism, if a ray incident at an angle of $30^{\circ}$. The angle between the emergent ray and the second refracting surface of the prism is :

asked Dec 19, 2018 by pady_1

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A short bar magnet with its north pole facing north forms a neutral point at $P$ in the horizontal plane. If the magnet is rotated by $90^{\circ}$ is the horizontal plane, the net magnetic induction at $P$ is : (Horizontal component of earth's magnetic field = $B_H$ )

asked Dec 19, 2018 by pady_1

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Two similar bar magnets $P$ and $Q$ each of magnetic moment $M$ are taken. If $P$ is cut along its axial line and $Q$ is cut along its equatorial line all the four pieces obtained have each of :

asked Dec 19, 2018 by pady_1

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There is no couple acting when two bar magnets are placed coaxially separated by a distance because :

asked Dec 19, 2018 by pady_1

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The pole strength of a $12\;cm$ long bar magnet is $2.0 \; Am$. The magnetic induction at a point $10\;cm$ away from the centre of the magnet on the axial line is : $\begin{pmatrix} \frac{\mu_0}{4 \pi}= 10^{-7} Hm^{-1} \end{pmatrix}$

asked Dec 19, 2018 by pady_1

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Electric charges of $1\; \mu C, \; 1 \; \mu C$ and $2 \mu C$ are placed in air at the corners of $A, B$ and $C$ respectively of an equilateral triangle $ABC$ having the length of the side $10\;cm$. The resultant forces at $C$ is : $\begin{pmatrix} \frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \frac{N m^{2}}{C^2} \end{pmatrix}$

asked Dec 19, 2018 by pady_1

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A charged particle of mass $3 \times 10^{-6} kg$ is held stationary in space in an electric field of strength $10^6 NC^{-1}$ directed vertically downwards. The charge on the particle is : $(g = 10\; ms^{-2})$

asked Dec 19, 2018 by pady_1

1 answer

Two long parallel copper wires carrying currents in the opposite directions of 5 A each. If the wires are separated by a distance of $0.5\;m$, then the force per unit length between the two wires is :

asked Dec 19, 2018 by pady_1

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