Recent questions tagged 2013

The extent of charge of lead accumulator is determined by

asked Sep 19, 2013 by meena.p

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During the electrolysis of copper sulphate aqueous solution using copper electrode, the reaction taking place at the cathode is :

asked Sep 19, 2013 by meena.p

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The vapour pressure in mm of $Hg,$ of an aqueous solution obtained by adding 18 g of glucose $(C_6H_{12}O_6)$ to $180\;g$ of water at $100^{\circ}$ is :

asked Sep 18, 2013 by meena.p

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Which one of the following is an isotonic pair of solutions?

asked Sep 18, 2013 by meena.p

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At $T(k),$ the ratio of kinetic energies of $4\;g$ of $H_{2_{(g)}}$ and $8\;g$ of $O_{2_{g}}$ is :

asked Sep 18, 2013 by meena.p

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Which one of the following is an example of disproportionation reaction?

asked Sep 18, 2013 by meena.p

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Which one of the following statement is correct?

asked Sep 18, 2013 by meena.p

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Identify the correct set:

asked Sep 18, 2013 by meena.p

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The number of elements present in fourth period is :

asked Sep 18, 2013 by meena.p

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The basic of quantum mechanical model of an atom is :

asked Sep 18, 2013 by meena.p

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The number of radial nodes of $3s$ and $2p$ orbitals respectively are :

asked Sep 18, 2013 by meena.p

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Of the following, $NAND$ gate is

asked Sep 18, 2013 by meena.p

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The base current in a transistor circuit changes from $45\;\mu A$ to $140\;mu A$. Accordingly, the collector current changes from $0.2\;mA$ to $4.00\;mA$. The gain in current is

asked Sep 18, 2013 by meena.p

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A $U^{235}$ nuclear reactor generates energy at a rate of $3.70 \times 10^7\; J/s$ Each fission liberates $185\;MeV$ useful energy. If the reactor has to operate for $144 \times 10^4$ seconds, then the mass of the fuel needed is (Assume Avogadro's number $=6 \times 10^{23} \;mol^{-1},1 eV=1.6 \times 10^{-19}\;J)$

asked Sep 18, 2013 by meena.p

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The radius of $_{72}Te^{125}$ nucleus is $6$ fermi . The radius of $_{13}AI^{27}$ nucleus in meters is

asked Sep 18, 2013 by meena.p

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The work function of a metal is $2$ eV. If a radiation of wavelength 3000 A is incident on it, the maximum kinetic energy of the emitted photo electrons is

asked Sep 18, 2013 by meena.p

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Initially a photon of wavelength $\lambda _1$ falls on photocathode and emits an electron of maximum energy $E_1$. If the wave length of the incident photon i changed to $\lambda _2$, the maximum energy of the electron emitted becomes $E_2$. Then value of hc (h= Planck's constant , c= velocity of light) is

asked Sep 18, 2013 by meena.p

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The sensitivity of a galvanometer that measures current is decreased by $\large\frac{1}{40}$ times by using shunt resistance of $10 \;\Omega$. Then, the value of the resistance of the galvanometer is

asked Sep 18, 2013 by meena.p

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A series $LCR$ circuit is connected across a source of alternating emf of changing frequency and resonates at frequency $f_0$. Keeping capacitance constant, if the inductance (L) is increased by $\sqrt 3$ times and resistance is increased (R) by 1.4 times, the resonant frequency now is

asked Sep 18, 2013 by meena.p

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The ends of an element of zinc are kept at a small temperature difference $ \Delta T$ and a small current (I) is passed through the wire. Then, the heat developed per unit time

asked Sep 18, 2013 by meena.p

1 answer

In the meter bridge experiment, the length AB of the wire is 1 m. The resistors $X$ and $Y$ have values $5 \Omega$ and $2 \Omega$ respectively. When a shunt resistance $S$ is connected to $X$, the balancing point is found to be $0.625\;m$ from A. Then, the resistance of the shunt is

asked Sep 18, 2013 by meena.p

1 answer

In the circuit shown in the figure, the current $'I'$ is

asked Sep 18, 2013 by meena.p

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Two metal plates of area 'A' from a parallel plate capacitor with air in between the plates. The distance between the plate is 'd'. A metal plate of thickness $\large\frac{d}{2}$ and of the same area A is inserted between the plates to from two capacitors of capacitance $C_1$ and $C_2$ as shown in the figure. If the effective capacitance of the two capacitor is $C'$ and the capacitance of the capacitor initially is $C$, then $\large\frac{C'}{C}$ is

asked Sep 18, 2013 by meena.p

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A deflection magnetometer is adjusted and a magnet moment M is placed on it in the usual manner and the observed deflection is $\theta$. The period of oscillation of the needed before setting to the deflection is $T$. When the magnet is removed, the period of oscillation of needle is $T_0$ before settling to $0^{\circ}-0^{\circ}$. If the earth's induced magnetic field is $B_{H},$ the relation between $T$ and $T_0$ is

asked Sep 18, 2013 by meena.p

1 answer

Two short bar magnets have their magnetic moments $1.2\;Am^2$ and $1.0\;Am^2$. They are placed on a horizontal table parallel to each other at a distance of $20\;cm$ between their centers, such that their north poles pointing towards geographic south. They have common magnetic equatorial line. Horizontal component of earth's field is $3.6 \times 10^{-5}$ T. Then, the resultant horizontal magnetic induction at mid point of the line joining their centers is $\bigg(\large\frac{\mu _0}{4 \pi}$$=10 ^{-7} 11/m\bigg)$

asked Sep 18, 2013 by meena.p

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A short bar magnet having magnetic moment $4\;Am^2,$ placed in a vibrating magnetometer, vibrates with a time period of 8 seconds. Another short bar magnet having a magnetic moment $8\;Am^2$ vibrates with a time period of $6$ seconds. If the moment of inertia of the second magnet is $9 \times 10^{-2}\;kg\;m^2,$ the moment of inertia of the first magnet is (Assume that both magnets are kept in the same uniform magnetic induction field.)

asked Sep 18, 2013 by meena.p

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Fresnel diffraction is produced due to light rays falling on a small obstacle. The intensity of light at a point on a screen beyond an obstacle depends on

asked Sep 18, 2013 by meena.p

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A microscope consists of an objective of focal length $1.9\;cm$ and eye piece of focal length $5\; cm$. The two lenses are kept at a distance of $10.5 \;cm.$ If the image is to be formed at the least distance of distinct vision, the distance at which the object is to be placed before the objective is (Least distance of distinct vision is 25 cm)

asked Sep 18, 2013 by meena.p

1 answer

The two surfaces of a concave lens, made of glass of refractive index $1.5 $ have the same radii of curvature R. It is now immersed in a medium of refractive index $1.75$ then the lens,

asked Sep 17, 2013 by meena.p

1 answer

A source of sound of frequency 640 Hz is moving at a velocity of $\large\frac{100}{3}$$\;m/s$ along a road, and is at an instant 30 m away from a point A on the road (as shown in figure). A person standing at $O$, $40 \;m$ away from the road hears sound of apparent frequency $v^1$. The value of $v^1$ is (velocity of sound= 340 \;m/s)

asked Sep 17, 2013 by meena.p

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An air column in a tube $32\; cm$ long, closed at one end, is in resonance with a tuning fork. The air column in another tube, open at both ends, of length 66 cm is in resonance with another tuning fork. When these two tuning fork.The air column in another tube, open at both ends, of length 66 cm is in resonance with another tuning fork. When these two tuning forks are sounded together, they produce $8$ beats per seconds. Then the frequencies of the two tuning forks are , (Consider fundamental frequencies only)

asked Sep 17, 2013 by meena.p

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Two bodies $A$ and $B$ of equal surface area have thermal emissivities of $0.01$ and $0.81$ respectively. The two bodies are radiating energy at the same rate. Maximum energy is radiated from the two bodies A and B at wavelengths $\lambda _A$ and $\lambda_B$ respectively. Difference in these two wavelength is $1 \; \mu m $. If the temperature of the body A is $5802\;K,$ then value of $\lambda _B$ is

asked Sep 17, 2013 by meena.p

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Efficiency of a heat engine whose sink is at a temperature of 300 k is $40 \;\%$. To increase the efficiency to $60 \;\%$, Keeping the sink temperature constant, the source temperature must be increased by

asked Sep 17, 2013 by meena.p

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Three moles of an ideal monoatomic gas undergoes a cyclic process as shown in the figure. The temperature of the gas in different states marked as 1,2,3 and 4 are 400 K, 700 K, 2500 K and 1100 K respectively. The work done by the gas during the process $1 -2 -3 -4 -1$ is (Universal gas constant R)

asked Sep 17, 2013 by meena.p

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On a temperature scale Y, water freezes at $ -160^{\circ} \;Y$ and boils at $-50^{\circ}Y$. On this $Y$ scale, a temperature of $340\;K$ is:

asked Sep 17, 2013 by meena.p

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A glass flask of volume one liter is filled completely with mercury at $0^{\circ}C$. Then flask is now heated to $100 ^{\circ} C.$ Coefficient of volume expansion of mercury is $1.82 \times 10^{-4} /^{\circ} C$ and coefficient of linear expansion of glass is $0.1 \times 10^{-4}/^{\circ} C$. During this process, amount of mercury which overflows is

asked Sep 17, 2013 by meena.p

1 answer

The terminal velocity of a liquid drop of radius 'r' falling through air is v. If two such drops are combined to form a bigger drop, the terminal velocity with which the bigger drop falls through air is ( Ignore any buoyant force due to air)

asked Sep 17, 2013 by meena.p

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A capillary tube of radius 'r' is immersed in water rises to a height of 'h'. Mass of water in the capillary tube is $5 \times 10^{-3}\;kg$. The same capillary tube is now immersed in a liquid whose surface tension is $\sqrt 2$ times the surface tension of water. The angle of contact between the capillary tube and this liquid is $45^{\circ}$. The mass of liquid which rises into the capillary tube now is , (in kg)

asked Sep 17, 2013 by meena.p

1 answer

A tension of $20 \;N$ is applied to a copper wire of cross sectional area $0.01\;cm^2$, Young's Modulus of copper is $1.1 \times 10^{11} \;N/m^2$ and Poisson's ratio is $0.32$. The decrease in cross sectional area of the wire is

asked Sep 17, 2013 by meena.p

1 answer

Two particles A and B of masses 'm' and '2m' are suspended from two mass less springs of force constants $K_1$ and $K_2$. During their oscillation, if their maximum velocities are equal, then ratio of amplitudes of A and B is

asked Sep 17, 2013 by meena.p

1 answer

The gravitational force acting on a particle, due to a solid sphere of uniform density and radius $R$, at a distance of $3R$ from the center of the sphere is $F_1$. A spherical hole of radius $(R/2)$ is now made in the sphere as shown in the figure. The sphere with hole now exerts a force $F_2$ on the same particle. Ratio of $F_1$ to $F_2$ is :

asked Sep 17, 2013 by meena.p

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A uniform circular disc of radius R, lying on a friction less horizontal plane is rotating with an angular velocity $\omega$ about its own axis. Another identical circular disc is gently placed on the top of the first disc coaxially. The loss in rotational kinetic energy due to friction between the two discs, as they acquire common angular velocity is (I is moment of inertia of the disc)

asked Sep 17, 2013 by meena.p

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Moment of inertia of a body about an axis is $4\;kgm^2$. The body is initially at rest and a torque of $8\;Nm$ starts acting on it along the same axis. Work done by the torque in $20\;sec.$ in joules, is

asked Sep 17, 2013 by meena.p

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The upper half of an inclined plane with an angle of inclination $\phi$, is smooth while the lower half is rough. A body starting from rest at the top of the inclined plane comes to rest at the bottom of the inclined plane. Then the coefficient of friction for the lower half is

asked Sep 17, 2013 by meena.p

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A mass of $2.9 $ kg is suspended from a string of length $50\; cm$ and is at rest. Another body of mass $q00 \;g$, which is moving horizontally with a velocity of $150\;m/s$ strikes and sticks to it. Subsequently when the string makes an angle of $60^{\circ}$ with the vertical, the tension in the string is $(g=10 m/s^2)$

asked Sep 17, 2013 by meena.p

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Two bodies of mass 4 kg and 5 kg are moving along east and north directions with velocities 5 m/s and 3 m/s respectively. Magnitude of the velocity of center of mass of the system is

asked Sep 17, 2013 by meena.p

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A ball at rest is dropped from a height of 12 m. It looses $25 \%$ of its Kinetic energy on striking the ground and bounces back to a height 'h'. Then value of 'h' is

asked Sep 17, 2013 by meena.p

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Two wooden blocks of masses M and m are placed on a smooth horizontal surface as shown in figure. If a force P is applied to the system as shown in figure such that the mass m remains stationary with respect to block of mass M, then the magnitude of the force P is

asked Sep 17, 2013 by meena.p

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A particle is projected from the ground with an initial speed of v at an angle of projection $\theta$. The average velocity of the particle between its time of projection and time it reaches highest point of trajectory is

asked Sep 17, 2013 by meena.p

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The work done in moving an object from origin to a point whose positiion vector is $\overrightarrow {r}=3 \hat {i}+ 2 \hat j-5 \hat k$ by a force $\overrightarrow {F}=2 \hat {i}- \hat j- \hat k$ is :

asked Sep 17, 2013 by meena.p

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