A to Z Exams

Two organ (open) pipes of lengths 50 cm and 51 cm produce 6 beats/s. Then the speed of sound is nearly

Un polarized light of intensity I0 is incident on a polarizer and the emerging light strikes a second polarizing filter with its axis at 450 to that of the first.The intensity of the emerging beam

The velocity of propagation of sound is 330 m/s, in air. If the third harmonic of the fundamental that can be exerted in an open ended tube is 450 Hz, the length of the tube is :

A condenser of capacity 10 μF is charged to a potential of 500 V. Its terminals are then connected to those of an uncharged condenser of capacity 40 μF. The loss of energy in connecting them together is

The plates of a parallel plate capacitor are charged upto 200 volts. A dielectric slab of thickness 4 mm is inserted between its plates. Then, to maintain the same potential difference between the plates of the capacitor, the distance between the plates is increased by 3.2 mm. The dielectric constant of the dielectric slab is :

Two charges 8C and -6C are placed at a distance of separation d between them and exerts a force of magnitude  F on each other. If a charge 8C is added to each of these and they are brought nearer to by a distance d/3, the magnitude of force between them

The current decays from 5A to 2A in 0.01s in a coil. The emf induced in a coil nearby it is 30V. The mutual inductance between the coils is

One junction of thermo couple is at 00C and the other junction is heated .Maximum current in the thermo couple is observed when hot junction is at 2400C.The temperature of the hot junction at which the direction of current reverses is

Two bodies of 6 kg and 4 kg masses have their velocity   5i^-2j^+10k^   and   10i^-2j^+5k^ respectively. Then the velocity of their centre of mass is

When a vibrating tuning fork is placed on a sound box of a sonometer, 8 beats per second are heard when the length of the sonometer wire is kept at 101 cm or 100 cm. Then the frequency of the tuning fork is (consider that the tension in the wire is kept constant)

A stretched wire of some length under a tension is vibrating with its fundamental frequency. Its length is decreased by 45% and tension is increased by 21%.Now its fundamental frequency

a sonometre has 25 forks. Each produces 4 beats with the next one. If the max frequency is 288Hz,which is the frequency of last fork. The lowest frequency is

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:

When a uniform wire of radius r, is stretched by a 2 kg weight the increase in its length is 2.00 mm. If the radius of the wire is r/2 and other conditions remaining the same, the increase in its length is

A plastic tube containing few stones is floating in a tank of water. If the stones are unloaded, the water level :

When an unknown resistance of 4Ω are connected in the left and right gaps of a meterbridge,the balance point is obtained at 50cm.The shift in the balance point if a 4 Ω resistance is now connected in parallel to the right gap is

when a wave traverses a medium , the displacement of a particle located at 'x' at a time  't' is given by  y=a sin (bt - cx) , where a,b and c are constants of the wave , which of the following is a quantity with dimensions

An eraser weighing 2N is pressed against the black board with a force of 5N. If the co-efficient of friction is 0.4. How much force parllel to the black board is required to slide the eraser upwards

Dispersive power of the material of a prism is 0.0221.If the deviation produced by it for yellow colour is 380,then the angular dispersion between red and violet colour is

In a potentiometer using two cells in series gave a balance length 600cm. When the same cells are connected opposing each other then balance length is 100cm. The ratio of emf’s of the cells is

A body is projected from the earth at angle 300 with the horizontal with some intial velocity. If its range is 20 m, the maximum height reached by it is : (in metres)

S.I unit of electrical conductivity

A block of mass 10kg lying on a smooth horizontal surface is being pulled by means of a rope of mass 2kg.If a force of 36N is applied at the end of the rope. The tension at the midpoint of the rope is

In an n-type semiconductor, the Fermi energy level lies

A body 'A' starts from rest with an acceleration 'a1'. After 2 seconds another body 'B' starts from rest with an acceleration a2.If they travel equal distance in the 5th second after the start of 'A'.a1:a2 equal to:

The liquids at temperature 600C and 300C respectively have masses in the ratio 3 : 4 and their specific heats in the ratio 4 : 5. If the two liquids are mixed, the resultant temperature is:

When a liquid in a glass vessel, is heated its apparent expansion is 10.30 x 10-4same liquid when heated in a metal its apparent expansion 10.06 x 10-4/0C. The coefficient of linear expansion of the metal is : (coefficient of linear expansion of glass = 9 x 10-6/0C):

Which one of the following statement is true ?

The force acting on a charge of 10-10C placed in an electric field of intensity 600 V/m is

A large tank filled with water to a height h is to be emptied through a small hole at the bottom The ratio of times taken for the level of water to fall from h to h/2 and h/2 to zero is

A 100 PFcapacitor is charged to a potential difference of 24V.It is connected to an uncharged capacitor 20PF.what will be the new potential difference across 100PF capacitor

An insulated cylindrical vessel filled with an insulated piston of negligible weight and negligible thickness at the midpoint of the vessel. The cylinder contains a gas at 0oC. When the gas is heated to 100oC, the piston moves through a length of 5 cm. Length of the cylindrical vessel in cm is

A body is thrown vertically upward with an initial velocity u reaches maximum height in 6 sec.The ratio of distance travelled by the body in the first and seventh second is :

Two wires of the same material but of different diameters carry the same current I. If the ratio of their diameters is 2 : 1, then the corresponding ratio of their mean drift velocities will be

In Young's double slit experiment,first slit has width four times the width of the second slit, the ratio of the maximum intensity to the minimum intensity in the interference fringe system is :

A motor cycle starts from rest and accelerates along a straight path at 2m/s2.At the starting point of the motor cycle, there is a stationary electric siren. How far has the motor cycle gone when the driver hears the frequency of the siren at 94% of its value when the motor cycle was at rest?(speed of sound=330ms-1)

A glass tube 1.5m long and open at both ends, is immersed vertically in a water tank completely. A tuning fork of 600Hz is vibrated and kept at the upper end of tube and tube is gradually raised out of water.The total number of resonances heard before when the tube comes out of water, taking velocity of sound as 330m/sec. is

A transformer steps up an A.C. voltage from 230V to 2300V. If the number of turns in the secondary coil is 1000, the number of turns in the primary coil will be

A potentiometer having a 4m long wire is connected to the terminals of a battery of constant output voltage. A Leclanche cell has a balancing length of 1m. If the length of the potentiometer wire is increased by 1m, then the position of the null point is

A convex lens of focal length 0.15m is made of a material of refractive index 3 / 2. When it is placed in a liquid, its focal length is increased by 0.225 m. The refractive index of the liquid is

Temperature of cold junction in a thermo- couple is 100C and neutral temperature is 2700C, then the temperature of inversion is

A long straight wire carries an electric current of 2A.The magnetic induction at a perpendicular distance of 5m from the wire is (μ0=4πx10-7 Hm-1)

The work function of the nickel is 5 eV. When a light of wavelength 2000 Ao falls on it, it emits photo electrons in the circuit. Then the potential difference necessary to stop the fastest electrons emitted is (given h = 6.67 x  10-34 J-s)

The phase difference between two vibrating particles separated by a distance of 11 metres into medium through which a progressive wave is travelling is 13200.If the frequency of the disturbance is 105 Hz, the phase velocity of the progressive wave in ms-l

In n-p-n transistor, in CE configuration:(1)  The emitter is heavily doped than the collector.(2)  Emitter and collector can be interchanged.(3)  The base region is very thin but is heavily doped.(4)  The conventional current flows from base to emitter

The volume of a cinema theatre is 100mx60mx20m and total acoustic absorption in it is 6800metric sabine.The reverberation time in that theatre is

In a photoelectric cell, wavelength of the incident light is changed from 4000A0 to 3600A0. Change in stopping potential will be nearly

A cylindrical resonance tube open at both ends has a fundamental frequency “f’ in air.If half of the length is dipped vertically in water,the fundamental frequency of the air column will be

In a potentiometer experiment, when a resistance of 10 ohm is connected in parallel to the cell in secondary circuit , the balancing length is 350 cm. when 10 ohm resistance is replaced by 20 ohm resistance, the balancing length becomes 420 cm.The internal resistance of the cell in secondary circuit is

A tuning fork vibrating with a sonometer wire of length 20cm produces 5 beats per second. The beat frequency does not change if the length of the wire is changed to 21 cm. The frequency of the tuning fork must be

When two capacitors are joined in series the resultant capacity is 2.4 μF and when the same two are joined in parallel the resultant capacity is 10μF.their individual capacities are

A motor car of mass 300 kg is moving with a velocity of 25 m/s, by applying brakes the car was brought to rest in a distance of 15 metres. The force of retardation in newton is :

The angle of minimum deviation when light is incident at an angle of 450 on the refracting faces of an equilateral prism of refractive index 1.414 is

Two condensers of capacities 4 μF and 5 μF are joined in series. The potential difference across 5 μF is 10 V then the potential difference across 4 μF condenser is:

A vehicle sounding a whistle of frequency 256 Hz is moving on a straight road, towards a hill with a velocity of 10 ms-1 . The number of beats per second observed by a person travelling in the vehicle is : (Velocity of sound =330 ms-1)

A solid wooden block resting on a frictionless surface is hit by a bullet. The bullet gets embedded. During this process:

A rifle of 20 kg mass can fire 4 bullets per second. The mass of each bullet is 35 x 10-3 kg and its final velocity is 400 ms-1. Then what force must be applied on the rifle so that it does not move backwards while firing the bullets

A condenser of capacity 10μF is charged to a potential of 500V. Its terminals are then connected to those of an uncharged condenser of capacity 40μF. The loss of energy in connecting them together is

A potentiometer wire of length 100 cm has a resistance of 10 Ω. It is connected in series with a resistance and a cell of emf 2V and of negligible internal resistance. A source of emf 10 mV is balanced against a length of 40 cm of the potentiometer wire. The value of external resistance is:

An auditorium has volume of 105m3 and surface area of absorption 2 x 104m2.Its average absorption coefficient is 0.2 .The reverberation time of the auditorium in seconds is

A 25 watt,220 volt bulb and a 100 watt,220 volt bulb are connected in series across 440 volt line

Two soap bubbles combine to form a single bubble. In this process, the change in volume and surface area are respectively V and A. If P is the atmospheric pressure, and T is the surface tension of the soap solution, the following relation is true .

A highly conducting sheet of aluminium foil negligible thickness is placed between the plates of a parallel plate capacitor.If thecapacitance before the insertion of foil was 10μF,its value after the insertion of foil will be

A liquid does not wet the solid surface if the angle of contact is

Two strings of the same material and the same area of cross-section ae used in sonometre experiment.One is loaded with 12kg and the other with 3kg,the fundamental frequency of the first string is equal to the overtone of the second string.If the length of the second string is 100cm,then the length of the first string is

a spark is produced between two insulated surfaces maintained at a potential difference of 5 x 106 volt. The energy output is 10-5 J. The charge transferred during the spark is

Three condensers 1μF,2μF and 3μF are connected in series to a p.d of 330volt.The PD across the plates of 3μF is

The ratio of specific heats of a gas is γ.The change in internal energy of one mole of the gas, when the volume changes from V to 2V at constant pressure P is

An observer is moving away from a sound source of frequency 100 Hz. If the observer is moving with a velocity 49m/s and the speed of sound in air is 330m/s, the observed frequency is

A thin metal disc of radius 0.25 m and mass 2 kg starts from rest and rolls down an Inclined plane. If its rotational kinetic energy is 4 J at the foot of the inclined plane, then its linear velocity at the same point is:

A 2 kg mass moving on a smooth frictioriless surface with a velocity of 10 m/s, hits another 2 kg mass kept at rest in an elastic collision. After collision, if they move together:

A person aiming to reach the exactly opposite point on the bank of a stream is swimming with a speed of 0.5ms-1 at an angle of 1200 with the direction of flow of water.The speed of water in the stream, in ms-1, is:

A rod with linear charge density λ is bent in the shape of circular ring.The electric potential at the centre of the circular ring is

The area of the coil in a moving coil galvanometer is 15cm2 and has 20 turns.The magnetic inductions is 0.2T and the couple per unit twist of the suspended wire is 10-6 Nm per degree.If the deflection is 450,the current passing through it is

A coil of radius π meters,100 turns carries a current of 3A.The magnetic induction at a point on its axis at a distance equal to √3 times its radius from its centre is

Two short magnets AB and CD are in the X-Y plane and are parallel to X-axis and co-ordinates of their centres respectively are (0, 2) and (2, 0). Line joining the north-south poles of CD is opposite to that of AB and lies along the positive X-axis. The resultant field induction due to AB and CD at a point P (2, 2) is 100 x 10-7T. When the poles of the  magnet CD are reversed, the resultant field induction is 50 x 10-7 T. The value of magnetic moments of AB and CD (in Am2) are :

If in a Wheatstone bridge the battery and Galvanometer are interchanged, the condition for balance

A wire of length 1m and negligible mass is fixed at one end ,and a sphere attached to it at the other end.The sphere is projected horizontally with velocity√90ms-1 and it describes a vertical circle. The elongation in the wire when the sphere is at the top position is e.Now the elongation in the wire when the sphere is at bottom position is(g=10ms-2),the stress in the wire at bottom position is within elastic limit)

Power radiated by a black body at temperature T1 is P and it radiates maximum energy at a wavelength λ1.If the temperature of the black body is changed from T1toT2,it radiates maximum energy at a wavelength λ1/2.The power radiated at T2 is

An electron beam moving with a speed of 2x107ms-1 enters a magnetic field of induction 3x10-3T, directed perpendicular to its direction of motion. The intensity of electric field applied so that the electron beam is undeflected due to the magnetic field is

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

A train is approaching with a uniform velocity of 72kmph and the frequency of the whistle of that train is 480 Hz.The apparent increase in the frequency of that whistle heard by a stationary observer on the platform is(Velocity of sound in air is 340ms-1)

Along the x-axis, three charges q/2 , -q and q/2 are placed at x = 0, x = a and x = 2a respectively. The resultant electric potential at a point P located at a distance r from the charge -q ( a << r ) is ( εo is the permittivity of free space )

The number of turns in primary and secondary coils of a transformer is 50 and 200. If the current in the primary coil is 4 A, then the current in the secondary coil is

An intrinsic semi conductor has 1018/m3 free electron and is doped with pentavalent impurity of 1024/m3.Then the free electrons density order increases by

A source and an observer move away from each other, each with a velocity of 10 m/s. with respect to ground If the observer find the frequency of sound coming from tile source as 1950 Hz, the original frequency of the source is: (assume velocity of sound in air = 340 m/s)

Work done to increase the temperature of one mole of an ideal gas by 300C, if it is expanding under the condition V∝T2/3 is, (R =8.314 J/mole/0 K)

7N14+2He4→X+1H1 then ‘X’ is

In a compensated pendulum two rods of  different metals are used with their lengths in ratio of 2 : 3. The coefficients of linear expansions for metals in the ratio is :

An infinite number of charges each of magnitude q are placed on x-axis at distances of 1, 2, 4, 8, ….. meter from the origin. The intensity of the electric field at origin is

The resistance of a conductor is 1.08Ω.To reduce it to 1Ω,the resistance that must be connected is

In a hall a person receives direct sound from a source 120m away. He also receives waves from the same source which reach him after being reflected from the 25m high ceiling at a point midway between them. The two waves interfere constructively for wavelengths (in metre) of

The frequency of a tuning fork x is 5% greater than that of standard fork of frequency K.The frequency of another fork y is 3% less than that of K.When x and y are vibrated together 4 beats are heard per second.The frequencies of x and y are

A 2 kg body and 3 kg body have equal momentum. If the kinetic energy of 3 kg body is 10 Joules, the kinetic energy of 2 kg body will be, (in joules) :

A potentiometer having wire of 4m length is connected to the terminals of a battery with a steady voltage.A leclanche cell has a null points at 1m,If the length of the potentiometer wire is increased by 1m,the position of the null points is

A primary coil and secondary coil are placed close to each other. A current, which changes at the rate of 25 amp in a millisecond, is present in the primary coil. If the mutual inductance is 92x10-6 Henries,then the value of induced emf in the secondary coil is

A 4μF capacitor is charged by a 200V battery.It is then disconnected from the supply and is connected to another uncharged 2μF capacitor.During this process,Loss of energy(in J)is

A proton, a deuteron (nucleus of 1H2) and an α-particle with same kinetic energy enter a region of uniform magnetic field moving at right angles to the field. The ratio of the radii of their circular  paths is :

A tangent galvanometer properly adjusted gives a deflection of 300 when a certain current is passed through it. When the current is changed, then it gives a deflection of 450. The ratio of the current in the two cases is:

The focal length of the lenses of an astronomical telescope are 50 cm and 5cm. The length of the telescope when the image is formed at the least distance of distinct vision is: