Recent questions tagged neet

Symbolic representation of four logic gates are shown as : Pick out which ones are for AND, NAND and NOT gates, respectively :

asked Aug 16, 2018 by pady_1

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In forward biasing of the p-n junction :

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If a small amount of antimony is added to germanium crystal :

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A transistor is operated in common emitter configuration at $V_C = 2V$ such that a change in the base current from 100 µA to 300 µA produces a change in the collector current from 10 mA to 20 mA. The current gain is :

asked Aug 16, 2018 by pady_1

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A nucleus $_n^m{X}$ emits one α particle and two β– particles. The resulting nucleus is :

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Fusion reaction takes place at high temperature because :

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Photoelectric emission occurs only when the incident light has more than a certain minimum:

asked Aug 16, 2018 by pady_1

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The half life of radioactive isotope 'X' is 50 years. It decays to another element 'Y' which is stable. The two elements 'X' and 'Y' were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be :

asked Aug 16, 2018 by pady_1

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In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by :

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Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be :

asked Aug 16, 2018 by pady_1

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Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de-Broglie wavelength associated with the electrons would

asked Aug 16, 2018 by pady_1

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In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding stopping potential is :

asked Aug 16, 2018 by pady_1

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A biconvex lens has a radius of curvature of magnitude 20 cm. Which one of the following options describe best the image formed of an object of height 2 cm placed 30 cm from the lens ?

asked Aug 16, 2018 by pady_1

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Which of the following is not due to total internal reflection ?

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The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is :

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The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is :

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Sound waves travel at $350 m/s$ through brass. The wavelength of a 700 Hz acoustic wave as it enters brass from wave air :

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Out of the following functions representing motion of a particle which represents SHM : (A) $y = \sin \omega t - \cos \omega t $ (B) $ y = \sin^3 \omega t $ (C) $ y = 5 \cos (\frac{3 \pi}{4} - 3 \omega t)$ (D) $ y = 1 + \omega t + \omega^2 t^2$

asked Aug 16, 2018 by pady_1

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Two waves are represented by the equations $y_1 = a \sin (wt + kx + 0.57) m$ and $ y_2 = a \cos (wt + kx) m, where \;$x$\; is\; in\; meter\; and\; $t in sec. The phase difference between them is :

asked Aug 16, 2018 by pady_1

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A particle of mass m is released from rest and follows a parabolic path as shown. Assuming that the displacement of the mass from the origin is small which graph correctly depicts the position of the particles as a function of time ?

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During an isothermal expansion, a confined ideal gas does - 150 J of work against its surroundings. This implies that :

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When 1 kg of ice at $0^oC$ melts to water at $0^oC$, the resulting change in its entropy, taking latent heat of ice to be $80 \; Cal/gm$ is :

asked Aug 16, 2018 by pady_1

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An ac voltage is applied to a resistance R and the inductive reactance are both equal to $3 \Omega$, the phase difference between the applied voltage and the current in the circuit is :

asked Aug 16, 2018 by pady_1

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In an ac circuit an alternating voltage $e = 200 \sqrt{2} \sin 100 \; t\; volts$ is connected to a capacitor of capacity $1 \mu F$. The r.m.s. value of the current in the circuit is :

asked Aug 16, 2018 by pady_1

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The current i in a coil varies with time as shown in the figure. The variation of induced emf with time would be :

asked Aug 16, 2018 by pady_1

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A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron :

asked Aug 16, 2018 by pady_1

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The electric and the magnetic field, assiociated with an e.m wave, propagating along the +z - axis, can be represented by :

asked Aug 16, 2018 by pady_1

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There are four light-weight -rood samples A, B, C, D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted : (a) A is feebly repelled (b) B is feebly attracted (c) C is strongly attracted (d) D remains unaffected Which one of the following is true ?

asked Aug 16, 2018 by pady_1

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The power obtained in a reactor using $U^{235}$ disintegration is 1000 kW. The mass decay of $U^{235}$ per hour is :

asked Aug 16, 2018 by pady_1

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A current carrying closed loop in the form of a right angle isoceles triangle ABC is placed in a uniform magnetic field acting along AB. If the magnetic force on the arm BC is $\overrightarrow{F}$ , the force on the arm AC is :

asked Aug 16, 2018 by pady_1

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The rate of increase of thermo - e.m.f. with temperature at the neutral temperature of a thermocouple :

asked Aug 16, 2018 by pady_1

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A current of 2 A flows through a $2 \Omega$ resistor when connected across a battery. The same battery supplies a current of 0.5 A when connect across a $ 9 \Omega$ resistor. The internal resistance of the battery is :

asked Aug 16, 2018 by pady_1

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If power dissipated in the $9 \Omega$ resistor in the circuit shown is 36 Watt, the potential difference across the $2 \Omega$ resistor is :

asked Aug 16, 2018 by pady_1

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A parallel plate condenser have a uniform electric field $E(V/m)$ in the space between the plates. If the distance between the plates is $d(m)$ and area of each plate is $A(m^2)$ the energy (joules) stored in the condenser is :

asked Aug 16, 2018 by pady_1

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Four electric charge +q, +1, - q and -q are placed at the corners of a square of side 2L. (see figure). The electric potential at point A, midway between the two charge +q and +q, is :

asked Aug 16, 2018 by pady_1

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A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will :

asked Aug 16, 2018 by pady_1

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Force F on a particle moving in a straight line varies with distance d as shown in the figure. The work done on the particle during its displacement of 12 m is :

asked Aug 16, 2018 by pady_1

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A missile is fired for maximu range with an initial velocity of 20 m/s. If $g = 10\; m/s^2$ , the range of the missile is :

asked Aug 16, 2018 by pady_1

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A body is moving with velocity 30 m/s towards east. After 10 seconds its velocity becomes 40 m/s towards north. The average acceleration of the body is :

asked Aug 16, 2018 by pady_1

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The potential energy of a system increases if work is done :

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A radioactive nucleus of mass M emits a photon of frequency $\nu$ and the nucleus recoils. The recoil energy will be -

asked Aug 16, 2018 by pady_1

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A planet moving along an elliptical orbit is closest to the sun at a distance $r_1$ and farthest away at a distance of $r_2$. If $v_1$ and $v_2$ are the linear velocities at these points respectively, then the ratio $\frac{v_1}{v_2}$ is :

asked Aug 16, 2018 by pady_1

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A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The impulse experienced by the body is -

asked Aug 16, 2018 by pady_1

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A particle moves in a circle of radius 5 cm with constant speed and time period $0.2 \pi s$. The acceleration of the particle is :

asked Aug 16, 2018 by pady_1

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The instantaneous angular position of a point on a rotating wheel is given by the equation $\theta (t) = 2t^3 - 6 t^2$ The torque on the wheel becomes zero at :

asked Aug 16, 2018 by pady_1

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A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest :

asked Aug 16, 2018 by pady_1

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A person of mass 60 kg is inside a lift of mass 940 kg and presses the button on control panel. The lift starts moving upwards with an acceleration $1.0 m/s^2$. If $g = 10 ms^{-2}$, the tension in the supporting cable is :

asked Aug 16, 2018 by pady_1

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A boy standing at the top of a tower of 20 m height drops a stone. Assuming $g = 10 ms^{-2}$, the velocity with which it hits the ground is :

asked Aug 16, 2018 by pady_1

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The moment of inertia of a thin uniform rod of mass M and length L about an axis passing through its midpoint and perpendicular to its length is $I_0$. Its moment of inertia about an axis passing through one of its ends and perpendicular to its length is :

asked Aug 16, 2018 by pady_1

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The dimension of $(\mu_o \epsilon_o)^{-1/2}$ are :

asked Aug 16, 2018 by pady_1

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