Recent questions tagged set a

Identify the semiconductor devices whose characteristics are given below, in the order (a),(b),(c),(d) :

asked Mar 8, 2017 by meena.p

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In an experiment for determination of refractive index of glass of a prism by $i -\sigma$ , plot, it was found that a ray incident at angle $35 ^{\circ}$, suffers a deviation of $40^{\circ}$ and that it emerges at angle $79^{\circ}$.In that case which of the following is closest to the maximum possible value of the refractive index?

asked Mar 8, 2017 by meena.p

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A galvanometer having a coil resistance of $100 \Omega$ gives a full scale deflection, when a current of $1 \;mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\; A$ is :

asked Mar 8, 2017 by meena.p

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A pipe open at both ends has a fundamental frequency f in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now :

asked Mar 8, 2017 by meena.p

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A screw gauge with a pitch of $0.5\;mm$ and a circular scale with $50$ divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge and brought in contact, the $45^{th}$ division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is $0.5\;mm$ and the $25^th$ division coincides with the main scale line?

asked Mar 8, 2017 by meena.p

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Choose the correct statement :

asked Mar 7, 2017 by meena.p

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If a, b, c, d are inputs to a gate and x is its output, then, as per the following time graph, the gate is :

asked Mar 7, 2017 by meena.p

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Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively.Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed numbers of A and B nuclei will be:

asked Mar 7, 2017 by meena.p

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Radiation of wavelength $\lambda$ , is incident on a photocell. The fastest emitted electron has speed v. If the wavelength is changed to $\large\frac{3 \lambda}{4}$, the speed of the fastest emitted electron will be :

asked Mar 7, 2017 by meena.p

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The box of a pin hole camera, of length $L$, has a hole of radius a. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda$ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say $b_{min}$) when :

asked Mar 7, 2017 by meena.p

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An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer the tree appears :

asked Mar 6, 2017 by meena.p

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Arrange the following electromagnetic radiations per quantum in the order of increasing energy : <br> A : Blue light B : Yellow light C : X-ray D : Radiowave

asked Mar 6, 2017 by meena.p

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An arc lamp requires a direct current of 10 A at $80\; V$ to function. It is connected to a $220 \;V(rms), 50\; Hz$ AC supply, the series inductor needed for it to work is close to :

asked Mar 6, 2017 by meena.p

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Hysteresis loops for two magnetic materials A and B are given below : These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use :

asked Mar 6, 2017 by meena.p

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Two identical wires A and B, each of length ‘l ’, carry the same current I. Wire A is bent into a circle of radius R and wire B is bent to form a square of side ‘a’. If $B_A$ and $B_B$ are the values of magnetic field at the centres of the circle and square respectively, then the ratio $\large\frac{B_A}{B_B}$ is :

asked Mar 6, 2017 by meena.p

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The temperature dependence of resistances of $Cu$ and undoped Si in the temperature range $300 - 400 K$ , is best described by :

asked Mar 6, 2017 by meena.p

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A combination of capacitors is set up as shown in the figure. The magnitude of the electric field due to a point charge Q (having a charge equal to the sum of the charges on the $4 \mu F$ and $9 \mu F$ capacitors), at a point distant $30\; m$ from it, would equal :

asked Mar 6, 2017 by meena.p

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The region between two concentric spheres of radii $‘a’$ and $‘b’$, respectively (see figure), has volume charge density $\rho = \large\frac{A}{r}$, where A is a constant and r is the distance from the centre. At the centre of the spheres is a point charge Q. The value of A such that the electric field in the region between the spheres will be constant, is :

asked Mar 6, 2017 by meena.p

1 answer

A uniform string of length $20\;m$ is suspended from a rigid support. A short wave pulse in introduced at its lowest end. It starts moving up the string. The time taken to reach the support is : (take $g=10\;ms^{-2})$

asked Mar 6, 2017 by meena.p

1 answer

A particle performs simple harmonic motion with amplitude A. Its speed is trebled at the instant that it is at a distance $\large\frac{2A}{3}$ from equilibrium position. The new amplitude of the motion is :

asked Mar 2, 2017 by meena.p

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‘n’ moles of an ideal gas undergoes a process $A \to B$ as shown in the figure. The maximum temperature of the gas during the process will be :

asked Mar 2, 2017 by meena.p

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An ideal gas undergoes a quasi static, reversible process in which its molar heat capacity Cremains constant. If during this process the relation of pressure P and volume V is given by $PV^n= constant$, then n is given by (Here $C_P$ and $C_V$ are molar specific heat at constant pressure and constant volume, respectively) :

asked Mar 2, 2017 by meena.p

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A pendulum clock loses $12\;s$ a day if the temperature is $40 ^{\circ} C $ and gains $4s\;a$ day if the temperature is $20 ^{\circ}C$. The temperature at which the clock will show correct time, and the co-efficient of linear expansion $(\alpha)$ of the metal of the pendulum shaft are respectively :

asked Mar 2, 2017 by meena.p

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A satellite is revolving in a circular orbit at a height ‘h’ from the earth’s surface (radius of earth R; $h << R$ ). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth’s gravitational field, is close to : (Neglect the effect of atmosphere).

asked Mar 2, 2017 by meena.p

1 answer

A roller is made by joining together two cones at their vertices O.It is kept on two rails AB and CD which are placed asymmetrically (see figure), with its axis perpendicular to CD and its centre O at the centre of line joining AB and CD (see figure). It is given a light push so that it starts rolling with its centre O moving parallel to CD in the direction shown. As it moves, the roller will tend to :

asked Mar 2, 2017 by meena.p

1 answer

A person trying to lose weight by burning fat lifts a mass of $10\; kg$ upto a height of $1\; m\; 1000\;times$.Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up? Fat supplies $3.8 \times 10^7\;J$ of energy per kg which is converted to mechanical energy with a $20\%$ efficiency rate. Take $g = 9.8 ms^{-2}$:

asked Mar 1, 2017 by meena.p

1 answer

A point particle of mass $m$, moves along the uniformly rough track $PQR$ as shown in the figure.The coefficient of friction, between the particle and the rough track equals $\mu$. The particle is released, from rest, from the point P and it comes to rest at a point R. The energies, lost by the ball, over the parts, PQ and QR, of the track, are equal to each other, and no energy is lost when particle changes direction from PQ to QR.The values of the coefficient of friction $\mu$ and the distance $x (= QR),$ are, respectively close to :

asked Mar 1, 2017 by meena.p

1 answer

A particle of mass m is moving along the side of a square of side $‘a’$, with a uniform speed $v$ in the $x-y$ plane as shown in the figure : Which of the following statements is false for the angular momentum $\overrightarrow {L}$ about the origin?

asked Mar 1, 2017 by meena.p

1 answer

A student measures the time period of $100$ oscillations of a simple pendulum four times. The data set is $90\; s, 91\; s, 95\; s\; and\; 92\; s$. If the minimum division in the measuring clock is $1\; s$, then the reported mean time should be :

asked Mar 1, 2017 by meena.p

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The negation of $\sim S \vee ( \sim r \wedge s)$ is equivalent to :

asked Oct 16, 2015 by meena.p

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Let $\tan^{-1}y= \tan^{-1} x +\tan^{-1} \bigg( \large\frac{2x}{1-x^2}\bigg)$, Where $|x| < \large\frac{1}{\sqrt 3}$. Then a value of y is :

asked Oct 16, 2015 by meena.p

1 answer

If the angle of elevation of the top of a tower from three collinear points A,B and C, on a line leading to the foot of the tower, are $30^{\circ}, 45^{\circ}$ and $60^{\circ}$ respectively , then the ratio, $AB: BC$, is :

asked Oct 16, 2015 by meena.p

1 answer

The mean of the data set comprising of 16 observations is $16$. If one of the observation valued $16$ is deleted and three new observation valued $3,4$ and $5$ are added to the data, then the mean of the resultant data, is :

asked Oct 16, 2015 by meena.p

1 answer

If 2 identical balls are to be placed in 3 identical boxes, then the probability that one of the boxes contains exactly 3 balls is :

asked Oct 16, 2015 by meena.p

1 answer

Let $ \overrightarrow{a},\overrightarrow{b}$ and $\overrightarrow{c}$ be three non- zero vectors Such that no two of them are collinear and $(\overrightarrow{a} \times \overrightarrow{b}) \times \overrightarrow{c} =\large\frac{1}{3}$$ | \overrightarrow{b}||\overrightarrow{c}| \overrightarrow{a} $. If $\theta$ is the angle between vactors $\overrightarrow{b}$ and $\overrightarrow{c}$ then a value of $\sin \theta$ is :

asked Oct 15, 2015 by meena.p

1 answer

The equation of the plane containing the line $2x-5y+z=3;x+y+4z=5,$ and parallel to the plane, $x+3y+6z=1,$ is:

asked Oct 15, 2015 by meena.p

1 answer

The distance of the point $(1,0,2)$ from the point of intersection of the line $ \large\frac{x-2}{3} =\frac{y+1}{4} =\frac{z-2}{12}$ and the plane $x-y+z=16$, is:

asked Oct 15, 2015 by meena.p

1 answer

Let $O$ be the vertex and Q be any point on the parabola, $x^2=8y$ . If the point P divides the line segment OQ internally in the ratio $1:3$ , then the locus of P is :

asked Oct 15, 2015 by meena.p

1 answer

The area (in sq.units) of the quadrilateral formed by the tangents at the end points of the latera recta to the ellipse $\large\frac{x^2}{9} +\frac{y^2}{5}$$=1$ , is :

asked Oct 15, 2015 by meena.p

1 answer

The number of common tangents to be circles. $x^2+y^2-4x-6y-12=0$ and $x^2+y^2+6x+18y+26=0$ is

asked Oct 15, 2015 by meena.p

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Locus of the image of the point $(2,3)$ in the line $(2x-3y+4)+k(x-2y+3)=0; k \in R$ is a :

asked Oct 15, 2015 by meena.p

1 answer

The number of points, having both coordinates as integers, that lie in the interior of the triangle with vertices $(0,0),(0,41)$ and $(41,0)$ IS :

asked Oct 15, 2015 by meena.p

1 answer

Let $y(x) $ be the solution of the differential equation : $(x log x) \frac{dy}{dx}$$+y=2x \log x, (x \geq 1)$ Then $y(e) $ is equal to :

asked Oct 15, 2015 by meena.p

1 answer

The area (in sq.units) of the region described by : $[(x,y);y^2 \leq 2x\;and\;y \geq 4x-1]$ is

asked Oct 15, 2015 by meena.p

1 answer

The integral $\int\limits_2^4 \large\frac{\log x^2}{\log x^2+\log (36-12x+x^2)}$$dx$ is equal to :

asked Oct 15, 2015 by meena.p

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The integral $\int \large\frac{dx}{x^2(x^4+1)^{3/4}}$ equals :

asked Oct 15, 2015 by meena.p

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Let $f(x) $ be a polynomial of degree four having extreme values at $x=1$ and $x=2$ . If $\lim \limits_{ x \to 0} \bigg[ 1+ \frac{f(x)}{x^2} \bigg]$$=3$ , then $f(2)$ is equal to :

asked Oct 15, 2015 by meena.p

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The normal to the curve , $x^2+2xy-3y^2=0$ at $(1,1)$

asked Oct 15, 2015 by meena.p

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If the function $g(x) = \left\{ \begin{array} {1 1} k \sqrt {x+1}, & \quad 0 \leq x 3 \\ mx=2 ,& \quad 3 < x \leq 5 \end{array} \right. $ is differential, then the value of $k+m$ is :

asked Oct 15, 2015 by meena.p

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$\lim \limits_{x \to 0} \large\frac{(1- \cos 2x)(3 +\cos x )}{x \tan 4x}$ is equal to :

asked Oct 15, 2015 by meena.p

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