Recent questions tagged 2005

A magnetic needle is kept in a non-uniform magnetic field. It experiences :

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The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp, when not in use ?

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In a potentiometer experiment the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of $ 2 \Omega$, the balancing length becomes 120 cm. The internal resistance of the cell is :

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A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B. The time taken by the particle of complete one revolution is :

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The uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then :

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The phase difference between the alternating current and emf is $\pi/2$. Which of the following cannot be the constituent of the circuit ?

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A circuit has a resistance of $12 \Omega$ and an impedance of $15 \Omega$. The power factor of the circuit will be :

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An energy source will supply a constant current into the load, if its internal resistance is :

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The self-inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitance of :

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A coil of inductance 300 mH and resistance $2 \Omega $ is connected to a source of voltage $2V$. The current reaches half of its steady state value in :

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Two concentric coils each of radius equal to $2 \pi$ cm are placed at right angles to each other. 3A and 4A are the currents flowing in each coil respectively. The magnetic induction in $Wb/m^2$ at the centre of the coils will be : ($\mu_0 = 4 \pi \times 10^{-7} \; Wb/Am$)

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If $I_0$ is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled ?

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An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency ?

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The bob of a simple pendulum is a spherical hollow ball filled with water. A plugged hole near the bottom of the oscillating bob gets suddenly unplugged. During observation, till water is coming out, the time period of oscillation would :

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If a simple harmonic motion is represented by $\frac{d^2x}{dt^2} + \propto x = 0$, its time peroid is :

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When two tuning forks (fork 1 and fork 2) are sounded simultaneously, 4 beats per second are heard. Now, some tape is attached on the prong of the fork 2. When the tuning forks are sounded again, 6 beats per second are heard. If the frequency of fork 1 is 200 Hz, then what was the original frequency of fork 2 ?

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A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C, then the resultant capacitance is :

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Two thin wire rings each having a radius R are placed at a distance d apart with their axes coinciding. The charges on the two rings are $+q$ and $-q$. The potential difference between the centres of the two rings is :

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Two point charges $+8 q$ and $-2q$ are located at $x=0$ and $x=L$ respectively. The location of a point on the $x$-axis at which the net electric field due to these two point charges is zero is :

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A charged ball B hangs from a silk thread S, which makes an angle $\theta$ with a large charged conducting sheet P, as shown in the figure. The surface charge density $\sigma$ of the sheet is proportional to :

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When an unpolarized light of intensity $I_0$ is incident on a polarizing sheet, the intensity of the light which does not get transmitted is:

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Two thin, long, parallel wires, separated by a distance $d$ carry $a$ current of $i$ $A$ in the same direction. They will :

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A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be :

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One conducting U-tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed $\nu$, then the emf induced in the circuit in terms of $B, l$ and $\nu$, where $l$ is the width of each tube, will be :

asked Nov 5, 2018 by pady_1

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A fully charged capacitor has a capacitance $C$. It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity $s$ and mass $m$. If the temperature of the block is raised by $\Delta T$, the potential difference $V$ across the capacitance is :

asked Nov 5, 2018 by pady_1

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Two sources of equal emf are connected to an external resistance $R$. The internal resistances of the two sources are $R_1$ and $R_2 (R_2 > R_1)$. If the potential difference across the source having internal resistance $R_2$, is zero, then :

asked Nov 5, 2018 by pady_1

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In the circuit, the galvanometer $G$ shows zero deflection. If the batteries $A$ and $B$ have negligible internal resistance, the value of the resistor $R$ will be:

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Two voltameters, one of copper and another of silver, are joined in parallel. When a total charge $q$ flows through the voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are $z_1$ and $z_2$ respectively, the charge which flows through the silver voltameter is :

asked Nov 5, 2018 by pady_1

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A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 V, the resistance in Ohm's needed to be connected in series with the coil will be :

asked Nov 5, 2018 by pady_1

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A nuclear transformation is denoted by $X(n, \alpha) \to ^7_3 Li$. Which of the following is the nucleus of element $X$ ?

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In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be :

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In a common base amplifer, the phase difference between the input signal voltage and output voltage is :

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If the kinetic energy of a free electron doubles, its de-Broglie wavelength changes by the factor :

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The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy ?

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A thin glass (refractive index 1.5) lens has optical power of -5 D in air. Its optical power in a liquid medium with refractive index 1.6 will be :

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Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately, what is the maximum distance at which these dots can be resolved by the eye ? [Take wavelength of light = 500 nm]

asked Nov 5, 2018 by pady_1

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A fish looking up through the water sees the outside world, contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is 12 cm below the water surface, the radius of this circle in cm is :

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Two simple harmonic motions are represented by the equations $y_1 = 0.1 \sin (100 \pi t + \frac{\pi}{3} )$ and $y_2 = 0.1 \cos \pi t$. The phase difference of the velocity of particle 1, with respect to the velocity of particle 2 is :

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A Young's double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is :

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The function $\sin^2( \omega t)$ represents :

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A system goes from A to B via two process I and II as shown in figure. If $\Delta U_1$ and $\Delta U_2$ are the changes in internal energies in the process I and II respectively, then :

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The figure shows a system of two concentric spheres of radii $r_1$ and $r_2$ and kept at temperature $T_1$ and $T_2$, respectively. The radical rate of flow of heat in a substance between the two concentric spheres, is proportional to :

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The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is :

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If radius of the $^{27}_{13} Al$ nucleus is estimated to be 3.6 fermi, then the radius of $^{125}_{52} Te$ nucleus be nearly :

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Starting with a sample of pure $^{66}Cu, 7/8$ of it decays into Zn in 15 min. The corresponding half life is :

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A Photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed $\frac{1}{2}m$ away, the number of electrons emitted by photocahode would :

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The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm, is incident on it. The band gap in (eV) for the semiconductor is :

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The intensity of gamma radiation from a given source is $I$. On passing through 36 mm of lead, it is reduced to $\frac{I}{8}$. The thickness of lead, which will reduce the intensity to$\frac{I}{2}$ will be :

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A gaseous mixture consists of 16 g of helium and 16 g of oxygen. The ratio $\frac{C_p}{C_{\nu}}$ of the mixture is :

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A particle of mass 10 g is kept on the surface of a uniform sphere of mass 100 kg and radius 10 cm. Find the work to be done against the gravitational force between them, to take the particle far away from the sphere : (you may take $G=6.67 \times 10^{-11}\; Nm^2/kg^2$)

asked Nov 5, 2018 by pady_1

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