Recent questions tagged set-11

A zener diode is connected to a battery and a load as shown below : The currents $\;I,I_{Z}\;$ and $\;I_{L}\;$ are respectively

asked May 20, 2014 by yamini.v

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A radioactive nuclei with decay constant 0.5/s is being produced at a constant rate of 100 nuclei/s . If at t=0 there were no nuclei , the time when there are 50 nuclei is :

asked May 20, 2014 by yamini.v

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A photon of wavelength $\;\lambda\;$ is scattered from an electron , which was at rest .The wavelength shift $\;\bigtriangleup \lambda\;$ is three times of $\;\lambda\;$ and the angle of scattering $\;\theta\;$ is $\;60^{0}\;$ . The angle at which the electron recoiled is $\;\phi\;$ .The value of $\;tan \phi\;$ is : (electron speed is much smaller than the speed of light)

asked May 20, 2014 by yamini.v

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In a compound microscope the focal length of objective lens is 1.2 cm and focal length of eye piece is 3.0 cm .When object is kept at 1.25 cm in front of objective , final image is formed at infinity . Magnifying power of the compound microscope should be :

asked May 20, 2014 by yamini.v

1 answer

Two monochromatic light beams of intensity 16 and 9 units are interfacing .The ratio of intensities of bright and dark parts of the resultant pattern is :

asked May 20, 2014 by yamini.v

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An object is located in a fixed position in front of a screen .Sharp image is obtained on the screen for two positions of a thin lens are separated by 10 cm .The size of the images in two situations are in the ratio 3 : 2 . What is the distance between the screen and the object ?

asked May 20, 2014 by yamini.v

1 answer

An electromagnetic field wave of frequency $\;1 \times 10^{14} \;$ hertz is propagating along z - axis . The amplitude of electric field is 4 V/m .If $\;\in_{0}=8.8 \times 10^{-12}\;C^{2}/N-m^{2}\;$ , then average energy density of electric field will be :

asked May 20, 2014 by yamini.v

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A coil of circular cross - section having 1000 turns and $\;4\;cm^{2}\;$ face area is placed with its axis parallel to a magnetic field which decreases by $\;10^{-2}\;Wb\;m^{-2}\;$ in 0.01 s. The e.m.f induced in the coil is :

asked May 20, 2014 by yamini.v

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Three identical bars A,B and C are made of different magnetic materials .When kept in a uniform magnetic field , the field lines around them look as follows : Make the correspondence of these bars with their material being diamagnetic (D) ,ferromagnetic (F) and paramagnetic (P) :

asked May 20, 2014 by yamini.v

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Three straight parallel current carrying conductors are shown in the figure . The force experienced by the middle conductor of length 25 cm is :

asked May 20, 2014 by yamini.v

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In the circuit shown , current (in A) through the 50 V and 30 V batteries are , respectively :

asked May 20, 2014 by yamini.v

1 answer

A parallel plate capacitor is made of two plates of length l , width w and separated by distance d . A dielectric slab (dielectric constant K) that fits exactly between the plates is held near the edge of the plates .It is pulled into the capacitor by a force $\;F=-\large\frac{\partial U}{\partial x}\;$ where U is the energy of the capacitor up to distance x (See figure) .If the charge on the capacitor is Q then the force on the dielectric when it is near the edge is :

asked May 20, 2014 by yamini.v

1 answer

A cone of base radius R and height h is located in a uniform electric field rightarrow{E}$\;\over\;$ parallel to its base. The electric flux entering the cone is :

asked May 20, 2014 by yamini.v

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Two factories are sounding their sirens at 800 Hz. A man goes from one factory to other at a speed of 2 m/s.The velocity of sound is 320 m/s.The number of beats heard by the person in one second will be :

asked May 20, 2014 by yamini.v

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The angular frequency of the damped oscillator is given by , $\;w=\sqrt{\large\frac{k}{m}-\large\frac{r^{2}}{4m^{2}}}\;$ where k is the spring constant , m is the mass of the oscillator and r is the damping constant.If the ratio $\;\large\frac{r^{2}}{mk}\;$ is $\;8\%\;$ , the change in time period compared to the undamped oscillator is approximately as follows :

asked May 20, 2014 by yamini.v

1 answer

An ideal monoatomic gas is confined in a cylinder by a spring loaded piston of cross section $\;8.0 \times 10^{-3}\;m^{2}\;$.Initially the gas is at 300K and occupies a volume of $\;2.4\times10^{-3}\;m^{3}\;$ and the spring is in its relaxed state as shown in figure.The gas is heated by a small heater until the piston moves out slowly by 0.1 m .The force constant of the spring is 800 N/m and the atmospheric pressure is $\;1.0 \times 10^{5}\;N/m^{2}\;$ . The cylinder and the piston are thermally insulated .The piston and the spring are massless and there is no friction between the piston and the cylinder .The final temperature gas will be : (Neglect the heat loss through the lead wires of the heater.The heat capacity of the heater coil is also negligible)

asked May 20, 2014 by yamini.v

1 answer

During an adiabatic compression , 830 J of work is done on 2 moles of a diatomic ideal gas to reduce its volume by $\;50\%\;$.The change in its temperature is nearly : $\;(R=8.3JK^{-1}mol^{-1})\;$

asked May 20, 2014 by yamini.v

1 answer

A hot body , obeying Newton's law of cooling is cooling down from its peak value $\;80^{0}C\;$to an ambient temperature of $\;30^{0}C\;$ . It takes 5 minutes in cooling down from $\;80^{0}C\;$ to $\;40^{0}C\;$. How much time will it take to cool down from $\;62^{0}C\;$ to $\;32^{0}C\;$ ? (Given ln 2=0.693 ; ln 5=1.609)

asked May 20, 2014 by yamini.v

1 answer

An air bubble of radius 0.1 cm is in a liquid having surface tension 0.06 N/m and density $\;10^{3}\;kg/m^{3}\;$ . The pressure inside the bubble is $\;1100\;Nm^{-2}\;$ greater than the atmospheric pressure . At what depth is the bubble below the surface of the liquid ? $\;(g=9.8)\;ms^{-2}\;$

asked May 19, 2014 by yamini.v

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A tank with a small hole at the bottom has been filled with water and kerosene (specific gravity 0.8) . The height of water is 3 m and that of kerosene 2 m . When the hole is opened the velocity of fluid coming out from it is nearly : (take $\;g=10\;ms^{-2}\;$ and density of water =$\;10^{3}\;kg\;m^{-3}\;$)

asked May 19, 2014 by yamini.v

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The bulk moduli of Ethanol , Mercury and water are given as 0.9 ,25 and 2.2 respectively in units of $\;10^{9}\;Nm^{-2}\;$ . For a given value of pressure , the fractional compression in volume is $\;\large\frac{ \bigtriangleup V}{V}\;$. Which of the following statements about $\;\large\frac{\bigtriangleup V}{V}\;$ for these three liquids is correct ?

asked May 19, 2014 by yamini.v

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From a sphere of mass M and radius R , a smaller sphere of radius $\;\large\frac{R}{2}\;$ is carved out such that the cavity made in the original sphere is between its centre and the periphery . (See figure) . For the configuration in the figure where the distance between the centre of the original sphere and the removed sphere is 3R , the gravitational force between the two spheres is :

asked May 19, 2014 by yamini.v

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A thin bar of length L has a mass per unit length $\;\lambda\;$ , that increases linearly with distance from one end .If its total mass is M and its mass per unit length at the lighter end is $\;\lambda_{0}\;$ , then the distance of the centre of mass from the lighter end is :

asked May 19, 2014 by yamini.v

1 answer

The average mass of rain drops is $\;3.0 \times 10^{-5}\;$ kg and their average terminal velocity is 9 m/s . Calculate the energy transferred by rain to each square metre of the surface at a place which receives 100 cm of rain in a year .

asked May 19, 2014 by yamini.v

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A small ball of mass m starts at a point A with speed $\;v_{0}\;$ and moves along a frictionless track AB as shown . The track BC has coefficient of friction $\;\mu\;$ . The ball comes to stop at C at travelling a distance L which is :

asked May 19, 2014 by yamini.v

1 answer

A body of mass 5 kg under the action of constant force $\;\overrightarrow{F}=F_{x} \hat{i} + F_{y} \hat{j}\;$ has velocity at t=0s as $\;\overrightarrow{v}=(6 \hat{i} -2 \hat{j})\;m/s\;$ and at t=10s as $\;\overrightarrow{v}=+6\hat{j}\; m/s\;$ . The force $\;\overrightarrow{F}\;$ is :

asked May 19, 2014 by yamini.v

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The initial speed of a bullet fired from a rifle is 630 m/s . The rifle is fired at the centre of a target 700 m away at the same level as the target . How far above the centre of the target the rifle must me aimed in order to hit the target ?

asked May 19, 2014 by yamini.v

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In terms of resistance R and time T , the dimensions of ratio $\;\large\frac{\mu}{\in}\;$ of the permeability $\;\mu\;$ and permittivity $\;\in\;$ is :

asked May 19, 2014 by yamini.v

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The gas liberated by the electrolysis of Dipotassium succinate solution is :

asked May 19, 2014 by yamini.v

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Which one of the following is used as Antihistamine ?

asked May 18, 2014 by yamini.v

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Tischenko reaction is a modification of :

asked May 18, 2014 by yamini.v

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In allene $\;(C_{3}H_{4})\;$ , the type(s) of hybridization of the carbon atom is (are) :

asked May 18, 2014 by yamini.v

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Complete reduction of benzene - diazonium chloride with $\;Zn/HCI\;$ gives :

asked May 18, 2014 by yamini.v

1 answer

Which one of the following does not have a pyramidal shape ?

asked May 18, 2014 by yamini.v

1 answer

Consider the coordination compound , $\;[CO(NH_{3})_{6}]Cl_{3}\;$ . In the information of this complex , the species which acts as the Lewis acid is :

asked May 18, 2014 by yamini.v

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Shapes of certain interhalogen compounds are stated below . Which one of them is not correctly stated ?

asked May 18, 2014 by yamini.v

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A gaseous compound of nitrogen and hydrogen contains $\;12.5\%\;$ (by mass) of hydrogen . The density of the compound relative to hydrogen is 16 . The molecular formula of the compound is :

asked May 18, 2014 by yamini.v

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Which of the following statements about the depletion of zone layer is correct ?

asked May 14, 2014 by yamini.v

1 answer

Which of the following statements about $\;Na_{2}O_{2}\;$ is not correct ?

asked May 14, 2014 by yamini.v

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The correct order of bond dissociation energy among $\;N_{2} ,O_{2} , O_{2}^{-}\;$ is shown in which of the following arrangements ?

asked May 14, 2014 by yamini.v

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Which of the following series correctly represents relations between the elements from X to Y ? $\;X \to Y\;$

asked May 10, 2014 by yamini.v

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Based on the equation : $\; \bigtriangleup E = -2.0 \times 10^{-18} J\; (\large\frac{1}{n_{2}^{2}} - \large\frac{1}{n_{1}^{2}})\;$ the wavelength of the light that must be absorbed to excite hydrogen electron from level n=1 to level n=2 will be : $\;(h=6.625 \times 10^{-34} Js\;,C=3 \times 10^{8}\;ms^{-1})$

asked May 10, 2014 by yamini.v

1 answer

The molar heat capacity $\;(C_{p})\;$ of $\;CD_{2}O\;$ is 10 cals at 1000 K . The change in entropy associated with cooling of 32 of g of $\;CD_{2}O\;$ vapour from 1000 K to 100 K at constant pressure will be : (D=deuterium , at . mass = 2u)

asked May 10, 2014 by yamini.v

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The initial volume of a gas cylinder is 750.0 mL . If the pressure of gas inside the cylinder changes from 840.0 mm Hg to 360.0 mm Hg , the final volume the gas will be :

asked May 10, 2014 by yamini.v

1 answer

Given $\; Fe^{3+} (aq) + e^{-} \to Fe^{2+} (aq) \; ; E^{0} =+0.77 V \qquad Al^{3+} (aq) + 3e^{-} \to Al (s) \; ; E^{0} =-1.66 V \qquad Br_{2} (aq) +2 e^{-} \to 2 Br^{-} \; ; E^{0} =+1.09V \;$ . Considering the electrode potentials , which of the following represents the correct order of reducing power ?

asked May 10, 2014 by yamini.v

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In some solutions , the concentration of $\;H_{3}O^{+}\;$ remains constant even when small amounts of strong acid or strong base are added to them . These solutions are known as :

asked May 10, 2014 by yamini.v

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For the reaction ,$\;2N_{2}O_{5} \to 4 NO_{2}+O_{2}\;$ , the rate equation can be expressed in two ways $\;- \large\frac{d[N_{2}O_{5}]}{dt} = k \normalsize N_{2}O_{5}\;$ and $\;+ \large\frac{d[NO_{2}]}{dt} = k^{'} \normalsize N_{2}O_{5}\;$ $\;k\;$ and $\;k^{'}\;$ are related as :

asked May 10, 2014 by yamini.v

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Assuming that the degree of hydrolysis is small , the pH of 0.1 M solution of sodium acetate $\;(K_{a}=1.0 \times 10^{-5})\;$ will be :

asked May 10, 2014 by yamini.v

1 answer

The appearance of colour in solid alkali metal halides is generally due to :

asked May 10, 2014 by yamini.v

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If $\;\lambda_{0}\;$ and $\;\lambda\;$ be the threshold wavelength and wavelength of incident light , the velocity of photo electron ejected from the metal surface is :

asked May 10, 2014 by yamini.v

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