A to Z Exams

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

The magnitude of the force between parallel conductors, each of length 110 cm,carrying a current of 10A and separated by a distance of 10 cm is

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

Particles and their anti-particles have

When a metal surface is illuminated by a light of wavelength 400 nm and 250 nm The maximum velocities of the photo electrons ejected are v and 2v respectively.The work function of the metal is : (h= Planck's constant, C= velocity of light in air)

A current of 0.5A produes a deflection of 600 in tangent galvanometer. The current that produces a deflection of 300 in the same galvanometer is

Light wave of frequency 4x1014Hz and λ=5x10-7m passes through a medium.The refractive index μ then the focal length of lens is

Two point charges -q and +q are located at points (0, 0, -a) and (0, 0, a) respectively. The electric potential at a point (0, 0, z), where z > a

A sonometer is set on the floor of a lift.When the lift is at rest,the sonometer wire vibrates with fundamental frequency 256Hz.When the lift goes up with acceleration a=9g/16,the frequency of vibration of the same wire changes to

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

A uniform wire of length 20m and weighing 5kg hangs vertically. If g=10m/s2,then the speed of transverse waves at the middle of the wire is

A wheel has a speed of 1200 revolution per minute and is made to slow down at a rate of 4 radian/sec2. The number of revolutions it makes before coming to rest 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

A sonometre wire vibrating in 4 segments is in unison with the tuning fork. Keeping the same length, if the tension made 4 times the tuning fork can still be in resonance with the wire provided the wire now vibrates in

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

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 .

There are two holes one each along the opposite sides of a wide rectangular tank. The cross section of each hole is 0.01 m2and the vertical distance between the holes is one meter. The tank is filled with water. The net force on the tank in newton when the water flows out of the holes is: ( Density of water = 1000 kg/m3 )

A machine gun fires 360 bullets per minute. Each bullet moves with a velocity of 600ms-1, If the power of the gun is 5.4kw, the mass of each bullet is,

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 horizontal beam of vertically polarized light of intensity 43W/m2 is sent through two polarizing sheets. The polarizing direction of the first is 600 to the vertical , and that of the second is horizontal. The intensity of the light transmitted by the pair of sheets is (nearly)

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

The temperature of 5 moles of a gas at constant volume is changed from 1000C to1200C The change In internal energy is 80J. The total heat capacity of the gas at constant volume will be in J/K is

A capacitor of 8 μF is charged to a potential of 1000V. The energy stored in the capacitor is

Degenerate electron pressure will not be sufficient to prevent core collapse of 'white dwarf' if its mass becomes n times of solar mass. Value of n is:

The bridge of a sonometer is slightly displaced so that the length of wire is decreased by 0.5% and tension in the wire is increased by 1%.The fundamental frequency of wire

The de Broglie wavelength of an electron moving with a velocity of 1.5x108m/s is equal to that of a photon. The ratio of kinetic energy of the electron to that of the photon (C=3x108m/s)

There are 5 tube-lights each of 40W in a house.These are used on an average for 5 hours per day.In addition ,there is an immersion heater of 1500W used on an average for 1 hour per day.The number of units of electricity are consumed in a month is

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)

The natural frequency of an I.-C circuit is 1,25,000 cycle/s. Then the capacitor C is replaced by another capacitor with a dielectric medium of dielectric constant K. In this case, the frequency decreases by 25 kHz. The value of K is

Two identical bodies have temperatures 2770C  and  670C. If the surroundings temperature is 270C, the ratio of loss of heats of the two bodies during the same interval of time is (approximately)

For an electron in H-atom the frequency of photon for transition between levels 1 and 2 is V .The photon frequency for transition between levels 2 and 3 is closest to

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)

A man stands infront of a hill rock and fires a gun. He hears an echo after 1.5 sec. the distance of the hill rock form the man is (velocity of sound in air = 330m/s)

A certain number of beats are heard when two tuning forks of natural frequencies n1 and n2 are sounded together. The number of beats heard when one of the forks is loaded :

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

Assertion (A): Propagation of light through an optical fibre is due to total internal reflection taking place at the core-clad interface.Reason (R): Refractive index of the material of the core of the optical fibre is greater than that of air.

The magnetic induction at a point, distance x from the centre, on the axis of a circular current carrying coil is inversely proportional to (if x > > radius of coil) :

If 9.8 gms of H2SO4 is neutralized exactly with strong alkali ,the heat evolved is(?H of neutralization is 13.6 K.cal)

A steady current is set up in a metallic wire of non-uniform cross-section. Then the drift velocity related the area of cross-section (A) as

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:

The elementary particles heavier than nucleons are called

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

Thomson coefficient of a conductor is 10μV/K.The two ends of it are kept at 500C and 600C respectively.Amount of heat absorbed by the conductor when a charge of 10C flows through it is

The neutral temperature of a thermo couple is5000C.If cold junction is at 300C the inversion temperature is

A circular coil of radius 11cm,carries and current of 2.5 amperes.If it has 700 turns,the flux density at the centre of the coil is

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

Twelve cells, each having emf E.volts are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12 cell battery is connected in series with an ammeter, an external resistance R ohms and a two-cell battery (two cells of the same type used earlier, connected perfectly in series). The current in the circuit when the 12-cell battery and 2-cell battery aid each other is 3A and is 2A when they oppose each other. Then, the number of cells in 12-cell battery that are connected wrongly is :

The magnetic induction at the centre due to motion of electron in first Bohr orbit is B. magnetic filed due to the motion of electron in second Bohr orbit at the centre will bw

A magnetic needle lying parallel to a magnetic field is turned through 600.The work does on it is w. The torque required to maintain the magnetic needle in the position mentioned above is

A whistle of frequency 540 Hz rotates in a horizontal circle of radius 2 m at an angular speed of 15 rad/s. The highest frequency heard by a listener at rest with respect to the centre of circle (velocity of sound in air = 330 ms-1)

A parallel plate capacitor has a capacity 80x10-6 when air is present between the plates.The volume between the plates is then completely filled with a dielectric slab of dielectric constant 20. The capacitor is now connected to a battery of 30 V by wires. The dielelctric slab is then removed. Then, the charge that passes now through the wire 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

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

A transverse wave propagating on a stretched string of linear density 3 x 10-4 kg m-1 is represented by the equation y = 0.2sin (1.5x - 60t) where x is in meters and t is in seconds. The tension in the string (in newton) is

At least how many thermal neutrons should be available to start a fission reaction

In a meter bridge a 30 Ω resistance is connected in the left gap and a pair of resistances P and Q in the right gap. Measured from the left, the balance point is 37.5 cm, when P and Q are in series and 71.4 cm when they are parallel. The values of P and Q (in Ω ) are

A wave of frequency 500Hz has a velocity of 360ms-1,what is the distance between two nearest points 600 out of phase?

A beam of charged particles of charge 'q' and mass m are accelerated from rest through a potential difference of 100 volts. They pass through crossed electric and magnetic fields which together produce null deflection. If these electronic and magnetic fields are respectively 15xl03 volts/m and 5weber/m2, then 'q/m' has a value, in coulomb/kg, equal to :

A long horizontal rigidly supported wire carries ia=96A.Directly above it and parallel to it at a distance, another wire of 0.144N weight per meter carrying a current ib=24A, in a direction opposite to that of ia is placed. If the upper wire is to float in air due to magnetic repulsion, then tits distance (in mm) from the lower wire is:

200MeV energy is released when one nucleus of 235U undergoes fission. The number of fissions per second required for producing a power of 1 megawatt

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 :

When an air bubble of radius r rises from the bottom to the surface of a lake. Its radius becomes 5r/4 (the pressure of the atmosphere is equal to the 10 m height to water column). If the temperature is constant and the surface tension is neglected the depth of the lake 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 :

The rate constant of the reaction at temperature 200K is 10 times than the rate constant at 400K.The activation energy of the reaction is

If 4 moles of an Ideal monoatomic gas at temperature 400 K is mixed with 2 moles of another ideal monoatomic gas at temperature 700 K, the temperature of the mixture is:

The refractive index of the material of a double convex lens is 1.5 and its focal length is 5 cm. If the radii of curvature are equal, the value of the radius of curvature (in cm) is

An observer is moving away from a sound source of frequency 100Hz. 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 body is projected vertically upwards from the surface of the earth with a velocity equal to half the escape velocity. If R is the radius of the earth, maximum height attained by the body from the surface of the earth is

Two trains are approaching each other on parallel tracks with same velocity.The whistle sound produced by one train is heard by a passenger in another train.If actual frequency of whistle is 620Hz and apparent increase its frequency is 100Hz,the velocity of one of the two trains is(Velocity of sound in air=335ms-1)

To measure the field B between the poles of an electromagnet,a small test loop of area 1cm2,resistance 10Ω and 20 turns is pulled out of it.A galvanometer shows that the total charge of 2μC passed through the loop.The value of resistance connected in series is

Two progressive waves each of frequency 10Hz traveling at 20cms-1 are superposed.In the resulting stationary wave,the distance between the successive nodes is

A north pole of strength πAm, is moved around a circle or radius 10 cm which lies around a straight conductor carrying a current of 10 A. The work done is nearly

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

Two charges of 10μC and -90μC are separated by a distance of 24cm.Electrostatic field strength from the smaller charge is zero at a distance of

A liquid of mass ‘m’ and specific heat C is heated to a temperature 2T.Anither liquid of mass m/2 and specific heat 2C is heated to a a temperature T.If these two liquids are mixed,the resulting temperature of mixture is

A body is sliding down on a rough inclined plane of inclination 45. The time taken by it to slide down on the rough inclined plane is 3 times the time taken by the body to slide down the smooth inclined plane of same inclination and length. The co-efficient of friction between the rough inclined plane and the body is

If the length of a stretched string is shortened by 40% and the tension is increased by 44% then the ratio of the final and initial fundamental frequencies is

In a series LCR a.c circuit R=50Ω and the impedance Z=100Ω. Then the phase difference between the current and applied voltage is (in radius)

Percentage of mass lost during the fission of 42U235 approximately is

A proton is projected with a velocity 107ms-1 ,at right angles to a uniform magnetic field of induction 100mT.The time(in seconds)taken by the proton to traverse 900 arc is:(Mass of proton=1.65x10-27kg and charge of proton = 1.6x10-19C

Thermo emf produce per 10C temperature difference between the junction is 0.005V.when cold junction is at 100C,and hot junction is at t0C,thermo emf produced is 0.5 V.,The value of t is

A pipe of length l1 closed at one end is kept in a chamber of gas of density ρ1.A second pipe open at both ends is placed in a second chamber of gas of density ρ2.The compressibility of both.The gases is equal.If frequency of first overtone in both the cases is equal,the length of the second pipe is

Along straight conductor carrying a current of 2A is in parallel to another conductor of length 5 cm and carrying a current 3A. They are separated by a distance of 10cm B due to first conductor at second conductor is

A galvanometer of resistance 100Ω gives full scale deflection with 5mA current.To convert it into a 5 volt range voltmeter,the value of resistance connected in series is

Two parallel plate air capacitors have the same separation. The plates of the first are squares of side 10cm.The plates of the second are squares of side 20cm.The ratio of the capacities respectively is

The magnetic induction at point 1cm away from a straight long current carrying Conductor is found to be 1x10-5wb/m2.the current that is passing through the conductor is

The natural frequency of a tuning fork p is 432 Hz. 3 beats/s are produced when tuning fork P and another tuning fork Q are sounded together. If P is loaded with wax, the number of beats increases to 5 beats/s. The frequency of Q is

When a high resistance R is connected in series with a voltmeter of resistance G, the range of the voltmeter increases 5 times. Then G:R will be

A fork gives 5beats/sec with a 40cm long sonometer wire.If the length of the wire is shortened by 1 cm,the number of beats/sec is still the same.The frequency of the fork is

A pipe having an internal diameter ‘D’ is connected to anther pipe of same size. water flows into the second pope through ‘n’ holes, each of diameter ‘d’. If the water in the first pipe has speed ‘V’, the speed of water leaving the second pipe is

The weight of a man in a lift moving upwards is 608 N while the weight of the same man in the lift moving downwards, with the same acceleration is 368 N. His normal weight in N is:

A coil of 40H inductance is connected in series with a resistance of 8Ω and this combination is connected to the terminals of a 2V battery. The inductive time constant of the circuit is (in seconds)

7N14+2He4→X+1H1 then ‘X’ is

The work function of a certain metal is 3.31 x 10-19 J. Then the maximum kinetic energy of photo electrons emitted by incident radiation of wavelength 5000 A0 is

Which of the following Statements is not correct when a junction diode is in forward bias ?

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

If two identical bar magnets, each of length l, pole strength m and magnetic moment  M are placed perpendicular to each other with their unlike poles in contact, the magnetic moment of the combination is :

The waves are prepared by the following equations y1=5 sin2π(10t-0.1x) y2=10sin2 π(20t-0.2x) ratio of intensities I2/I1 will be

If the work done in stretching a wire by 1mm is 2J,the work necessary for stretching another wire of same material but with double radius of cross-section and half the length by 1mm(in joule) 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: