Recent questions in 1998

The potential in the depletion layer is due to :

asked Dec 19, 2018 by pady_1

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A hole is :

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In the carbon cycle of fusion :

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Among electron, proton, neutron and $\alpha$-particle the maximum penetraion capacity is for :

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The number of $\alpha$ and $\beta$ particles, respectively, emitted in the radioactive decay $ _{90}X^{200} \to _{80}Y^{168}$ are :

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When $_{15}P^{30}$ decays to become $_{14}Si^{30}$ the particle released is :

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An electron remains undeflected when passing perpendicular to mutually perpendicular electric and magnetic fields. If the magnetic field is 8 Gauss and the electric field is $400\; V/m$, the velocity of the electron is :

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The radius of the Bohr orbit depends on $n$ as :

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The photoelectric work function of a metal surface is $2\;eV$. When light of frequency $1.5 \times 10^{15} Hz$ is incident on it, the maximum kinetic energy of the photo electrons, approximately is :

asked Dec 19, 2018 by pady_1

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A current carrying wire produces in the neighbourhood :

asked Dec 19, 2018 by pady_1

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A galvanometer has a resistance of $50 \; \Omega$ and a current of $0.01 \;A$ will cause full scale deflection. To convert this into an ammeter with full scale deflection for $5 \;A$, we have to connect approximately :

asked Dec 19, 2018 by pady_1

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If a long hollow copper pipe carries a current, the magnetic field produced will be :

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In a meter bridge the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be 20 cm. The value of the unknown resistance is :

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A wire of resistance $10 \Omega$ is elongated by $10 \%$, the resistance of the elongated wire :

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A parallel plate condenser with oil between the plates (dielectric constant of oil $K=2$) has a capacitance $C$. If the oil is removed, the capacitance of the capacitor becomes :

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The charges $+ 5 \; \mu C$ and $+ 10 \; \mu C$ are placed $20\; cm$ apart. The electric field at the mid point between the two charges is :

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Diamagnetic substance are :

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The null points are on the equatorial line of a bar magnet when the north pole of the magnet is pointing :

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Fraunhofer lines are due to :

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In the achromatic prism, we have :

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A compound microscope has an objective of focal length 4 mm and an eye piece of focal length 25 mm. The objective produces a real image at a distance of 180 mm. If the eye piece is in normal adjustment the magnification is :

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An object is placed 40 cm in front of a convex mirror of radius of curvature 20 cm. The image :

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A man stands in front of a hillock and fires a gun. He hears an echo after 1.5 s. The distance of the hillock from the man is (velocity of sound in air is 330 m/s) :

asked Dec 19, 2018 by pady_1

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A string in a musical instrument is 50 cm long and its fundamental frequency is 270 Hz. If the desired frequency of 1000 Hz is to be produced, the required string length is :

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The equation of wave is : <br> $y = 1.0 \cos 2 \pi (\frac{t}{0.02} - \frac{x}{10})$ where $t$ is in second. The frequency of the wave is :

asked Dec 19, 2018 by pady_1

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In order that heat is conducted from one part of a solid to another part, what is required is ?

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A lead bullet of mass 21g travelling at a speed of $100 \; m/s$ comes to rest in a wooden block. If no heat is taken away by the wood, the rise in temperature of the bullet in the wood nearly is (sp. heat of lead = $30 cal/kg^{\circ}C $) :

asked Dec 19, 2018 by pady_1

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The First Law of thermodynamics states that :

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One litre of helium gas at a pressure of 76 cm-Hg and temperature $27^{\circ}C$ is heated till its pressure and volume are doubled. The final temperature attained by the gas is :

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A real gas can be approximated to an ideal gas at :

asked Dec 19, 2018 by pady_1

1 answer

A glass flask of volume $200 \; cm^3$ is completely filled with mercury at $20^{\circ}C$. The amount of mercury that spilt over when the flask is heated to $80^{\circ}C$ is (coefficient of volume expansion for glass $27 \times 10^{-8} /^{\circ}C$, mercury $0.18 \times 10^{-8}/^{\circ}C$) :

asked Dec 19, 2018 by pady_1

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A steel bridge in a town is 200 m long. Where minimum temperature in winter is $10^{\circ}C$ and maximum in summer is $40^{\circ}C$. The change in length of the bridge from winter to summer is [ for steel alpha is $11 \times 10^{-6}/^{\circ}C$] :

asked Dec 19, 2018 by pady_1

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Neglecting gravity, the potential energy of a molecule of a liquid on the surface of the liquid when compared to the potential energy of a molecule inside the liquid is :

asked Dec 19, 2018 by pady_1

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The Poisson's ratio $\sigma$ should satisfy the relation :

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The equation of motion of a particle is given by $\frac{dp}{dt} + m \omega^2 n = 0$, where $p$ is the momentum and $n$ is the position. Then the particle :

asked Dec 19, 2018 by pady_1

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A satellite is revolving near the earth's surface. Its orbital velocity is :

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For an electron circulating around the nucleus, the centripetal force is supplied by :

asked Dec 19, 2018 by pady_1

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The maximum speed with which a car can be driven round a curve of radius 18 m without skidding (when $g = 10\;m/s^2$ and the coefficient of friction between rubber tyres and the roadway is $0.2$ ) is :

asked Dec 19, 2018 by pady_1

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Value of g :

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A stone tied to a string is rotated in a vertical circle. The minimum speed with which the string has to be rotated :

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Dimensions of ohm are same as (h = Planck's constant, e = charge) :

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The position of a particle is given by $\overrightarrow{r} = (\hat{i} + 2 \hat{j} - \hat{k} )$ momentum $\overrightarrow{p} = ( 3 \hat{i} + 4 \hat{j} - 2 \hat{k})$. The angular momentum is perpendicular to :

asked Dec 19, 2018 by pady_1

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If a body is in equilibrium under a set of non-collinear forces, the minimum number of forces has to be :

asked Dec 19, 2018 by pady_1

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A car starts from rest, attains a velocity of $36 \; km/h$ with an acceleration of $0.2 \;m/s^2$, travels $9 \; km$ with this uniform velocity and then comes to halt with a uniform deaceleration of $0.1\; m/s^2$. The total time of travel of the car is :

asked Dec 19, 2018 by pady_1

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A person standing on the edge of a well throws a stone vertically upwards with an initial velocity 5 m/s. The stone goes up, comes down and falls in the well making a sound. If the person hears the sound 3s after throwing, the water is at a depth from ground given by (neglect time of travel for the sound and take $g = 10\;m/s^2$):

asked Dec 19, 2018 by pady_1

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A person throws a bottle into a dustbin at the same heigh as he is 2 m away at an angle of $45^{\circ}$. The velocity of the throw is

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The relation $\overrightarrow{F} = m \overrightarrow{a}$, cannot be deducted from Newton's second law, if :

asked Dec 19, 2018 by pady_1

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A car of mass $400\; kg$ and travelling at $72\; km/h$ crashes into a truck of mass $4000\; kg$ and travelling at $9 \; km/h$, in the same direction. The car bounces back at a speed of $18\; km/h$. The speed of the truck after the impact is :

asked Dec 19, 2018 by pady_1

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A simple pendulum hanging freely and at rest is vertical because in that position :

asked Dec 19, 2018 by pady_1

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An iron block of sides $50\; cm \times 8 \; cm \times 15\; cm $ has to be pushed along the floor. The force required will be minimum when the surface in contact with ground is :

asked Dec 19, 2018 by pady_1

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