A to Z Exams

If π is Peltier coefficient,heat evolved at a junction when a current of 10 mA passes for 10 seconds in joules is

A 2 kg stone tied at the end of a string of 1 m length, is whirled along a vertical circle at a constant speed of 4 m/s. The tension in the string has a value of 52 N when the stone 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:

A light of length 75 cm is suspended from the ceiling horizontally by means of two vertical wires of equal length tied to its ends. One of the wires is made of steel of cross section 0.2 sq cm.The Position along the rod at which a weight may be hung to produce equal stresses.ysteel=20x1010 N/m2,Ybrass=10x1010N/m2

The length of a narrow closed pipe is L.The possible wavelengths of stationary waves forms in it are

If the angle of minimum deviation produced by an equilateral prosm is 300, the refractive index of material of prism 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)

When the angle of inclination of an inclined plane is θ, an object slides down with uniform velocity. If the same object is pushed with a initial velocity u on the same inclined plane; it goes up the plane and stops at a certain distance on the plane. Thereafter the body :

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

When a wire of length 10 m is subjected to a force of 100 N along its length, the lateral strain produced is 0.01 x 10-3 m. The Poisson's ratio was found to be 0.4. if the area of cross-section of wire is 0.025 m2, its Young's modulus is

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

The wave length of the Kαline for an element of atomic number 43 is λ.Then the wavelength of the Kαline for an element of atomic number 29,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 parallel plate capacitor has a capacitance of 10 micro farads without dielectric. A dielectric of dielectric constant 2 is used to fill exactly half the thickness between the plates. The capacitance in micro farads,now 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

An open pipe resonates to a frequency ‘f1’ and a closed pipe resonates to a frequency ‘f2’.If they are joined together to form a longer tube,then it will resonate to a frequency of(neglect end corrections)

The frequency of transverse vibrations in a stretched string is 200 Hz.If the tension is increased 4 times and the length is reduced to one fourth the original values,the frequency of vibrations will be

A transistor having a β equal to 80 has a change in base current of 250μA,then the change in collector current is :

A particle is projected from the ground with an initial velocity of 20ms-1 at an angle of 300 with horizontal. The magnitude of change in velocity in 0.5 seconds is(g=10ms-1)

Two positive charges q1=4x10-6C and q2=9x10-6C are placed 10cm apart in air. The position of a third charge to be placed between them, such that there will be no resultant force on it is

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:

Three charges –q, +q and –q are placed at the corners of an equilateral triangle of side a. The resultant electric force on a charge +q placed at the centroid O of the triangle is

When two unknown resistances are placed in the gaps of meterbridge,the null point is found to be 40cm from one end of the bridge wire.when one of the resistances is shunted with a 10 ohm coil,the null points is 25cm form the same end.The value of each of the unknown resistances is

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 frequency of a fork is 500 Hz.Velocity of sound in air is 350ms-1.The distance through which sound travel by the time the fork makes 125 vibrations is

Two strings x and y on a Veena playing the same note are slightly out of tune and produce 6 beats per second. The tension in x is slightly decreased and it is found tha the beats fall to 3 per second. If the original frequency of x is 324 Hz, the frequency of y is

Which of the following statements is not true in the case of 1 Huygen's eye piece

A motor car approaching a cliff with a velocity of 90 kmph sounds the horn and the echo is heard after 20 seconds.Assuming the velocity of sound in air to be 332m/s,the distance between the car and cliff when the horn is sounded is

One of the refracting surface of a prism of angle 300 is silvered. A ray of light incident at angle of 600 retraces its path. The refractive index of the material of a prism is

A light ray of wavelength λ is passing through a pin hole of diameter D and the effect is observed on a screen placed at a distance L from the pin hole. The approximations of geometrical optics are applicable if

The equation of a transverse wave is y=asin2π[t-(x/5)],then the ratio of maximum particle velocity and wave velocity is

A soap bubble of radius r is blown up to form a bubble of radius 2r under isothermal conditions. If T is the surface tension of soap solution, the energy spent in the blowing

In the Young's double slit experiment, the intensities at two points P1, and P2 on the screen are respectively I1, and I2. If P1, is located at the centre of a bright fringe and P2 is located at a distance equal to a quarter of fringe width from P1 then I1/I2 is

In a meterbridge experiment,the balance length is 40cm.the resistance in the gap opposite to this length of wire is 8 ohm.The resistance in the other gap is

A sonometer consists of two wires of same material whose radii are in the ratio2:3.The tension in thick wire is 4 times the tension in thin wire.If V is velocity of transverse were in thin wire,then the velocity of transverse wave in thick wire is

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

Two identical metal spheres possess +60C and -20C of charges.They are brought in contacts and then separated by 10cm.The force between them is

A man 50 kg is standing at one end on a boat of length 25 m and mass 200 kg. If he starts running and when he reaches the other end, he has a velocity 2 ms-1 with respect to the boat.The final velocity of the boat is : (in ms-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

In Youngs double slit experiment the separation between the slits is halved and the distance between the slits and screen is doubled .The fringe width is

A certain block weights 15N in air. But it weighs only 12N when completely immersed in water. When immersed in another liquid, it weighs 13N. The ratio of relative density of the block and the liquid

A photo-cathode is irradiated in turn by light of wavelengths 4000 A0 and 6200 A0 respectively. The ratio of the stopping potentials in the two cases is found to be 2:1. The work function of the photo-cathode is nearly

When a thin wedge-shaped film is illuminated by a parallel beam of light of wavelength 6000A0,7 fringes are observed in a certain region of the film.The number of fringes will be observed in the same region of the film if light of wavelength 4200A0 is used

A coil has 1,000 turns and 500cm2 as its area.The plane of the coil is placed at right angles to a magnetic induction field of 2x10-5web/m2.The coil is rotated through 1800 in 0.2 seconds.The average emf induced in the coil,in milli volts,is

In a transistor if IC/IE and IC/IB=β.If α varies between 20/21 and 100/101,then the value of β lies between

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)

Two long straight conductors are held parallel to each other at a distance 0.3m.If the conductors carry currents 2A and 8A in opposite directions,the distance of the neutral point from the conductor carrying smaller current is

A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in a uniform magnetic field of induction 2 tesla.If the magnetic field is perpendicular to the length of the wire,the force acting on the wire

The two surfaces of a biconvex lens has same radii of curvatures. This lens is made of glass of refractive index 1.5 and has a focal length 10 cm in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that the convex surfaces touch each other. If this  combination lens is immersed in water (refractive index = 4/3), its focal length (in cm) is :

A bullet of mass 10 g is fired horizontally with a velocity 1000ms-1 from a rifle situated at a height 50 m above the ground. If the bullet reaches the ground with a velocity 500ms-1, the work done against air resistance in the trajectory of the bullet is : (g=10ms-2)

Two wires A and B are of lengths 40 cm and 30 cm, A is bent into a circle of radius r and B into an arc of radius r. A current i1 passed.through A and i2 through B. To have the same magnetic inductions at the centre, the ratio of    i1  :   i2  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

A ray of light in air is incident on a glass plate at polarizing angle of incidence. It suffers deviation of 220 on entering glass. The angle of polarization is

With a standard rectangular bar magnet of length (l), breadth (b; b < < l) and magnetic moment M, the time period of the magnet in a vibration magnetometer is 4 s. If the magnet is cut normal to its length into four equal pieces, the time period (in seconds) with one of the pieces is :

In a thermo couple the temperature of the cold junction is 150C.If the temperature of inversion is 4850C,the neutral temperature of the thermo couple is

A steel wire of length L is stretched between two rigid supports and set in to vibration.The frequency of the second over tone produced by it is found to be f.The speed of transverse wave in the wire is

A piece of metal weighs 45gms in air and 25gms in a liquid  of density 1.5 X 103 kg-m-3 kept at 300 C . When the temperature of the liquid is raised to 400 C the metal piece weighs 27gms . The density of the liquid at 400 C is 1.25 X 103 kg-m-3 . The coefficient of linear expansion of metal 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

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)

An aluminum (resistivity ρ = 2.2 x 10-8 Ω-m) wire of a diameter 1.4 mm is used to make a4Ω resistor. The length of the wire 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 galvanometer of resistance 20Ω is to be shunted so that only 1% of the current passes through it. Shunt connected is

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:

When cold junction is at 00C variation of thermo emf(e) of Fe-Cu thermo couple with temperature of hot junction t is given as e=14t-0.02t2.Its neutral temperature 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

Four bulbs each marked 40 W. 250 V are connected in series with 250 V source. The total power output is

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

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

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

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

A coil has an inductance of 0.05H and 100 turns and 0.02A current is passed through it.Flux linked with coil 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

Youngs double slit experiment is conducted with light of wavelength λ.The intensity of the bright fringe is I0.The intensity at a point where path difference is λ/4 is given by

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

A free neutron decays spontaneously into :

A dielectric of thickness 5cm and dielectric constant 10 is introduced between the plates of a parallel plate capacitor having plate area 500 sq.cm and separation between the plates 10cm.The capacitance of the capacitor with dielectric slab is(ε0=8.8x10-12/N-m2)

The ratio of surface areas of the two spheres is 9:16.They are put in contact and a charge of 7μC is given to the system and they are separated. Then the intensity of the electric field at a distance of 100m from the centre of smaller sphere is

According to Moselay's law, the frequency of  (v) of the Kα - line and the atomic number (Z) of the element  have the relation (A and B are constants)

The centre of mass of three particles of masses 1 kg, 2 kg and 3 kg is at (2, 2, 2).The position of the fourth mass of 4 kg to be placed in the system as that the new centre of mass is at (0, 0, 0) 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)

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

A light ray is incident on a transparent medium of μ=1.732 at the polarizing angle.The angle of refraction is

To generate power of 3.2 MW, the number of fissions of U235 per minute is : (Energy released per fission =200 MeV; 1eV=1.6x10-19J)

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)

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 2 MeV proton is moving perpendicular to a uniform magnetic field of 2.5 tesla. The force on the proton is (mass of proton = 1.6 x 10-27 kg)

An iron load of 2kg is suspended in air from the free end of a sonometer wire of length 1m.A tuning fork of frequency 256Hz is in resonance with 1/√14 times the length of the sonometer wire.If the load is immersed in water,the length of the wire in meter that will be in resonance with the same tuning fork is (specific gravity of iron=8)

A man slides down on a telegraphic pole with  an acceleration equal to one-fourth of acceleration due to gravity. The frictional force between man and pole is equal to in terms of man's weight w

An n-p-n transistor power amplifier in C-E configuration gives :

Two charges of 50 μC and 100 μC are separated by a distance of 0.6m. The intensity of electric field at a point midway between them is

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

When an unknown resistance and a 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 4Ω resistance is now connected in parallel to the resistance in the right gap 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

Which one of the following statement is true ?

Two bar magnets A, B are placed one over the other and are allowed to vibrate in a vibration magnetometer. They make 20 oscillations per minute when the similar poles of A and B are on the same side, while they make 15 oscillations per minute when their opposite poles lie on the same side. If MA and MB are the magnetic moments of A and B and if MA > MB, the ratio of MA and MB is

To a charged particle which is moving with a constant initial velocity v, uniform magnetic field is applied in the direction ot the velocity :

When a monochromatic light of frequency v is incident on a metal, stopping potential is V0. Frequency of the incident light for which stopping potential becomes 2V0 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 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

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