A to Z Exams

In an experiment on photoelectric emission from a metallic surface, wavelength of incident light is 2xl0-7 m and stopping potential is 2.5 V. The threshold frequency of the metal (in Hz)   approximately   (charge  of electron e= 1.6 x 10-19 C  Planck's constant h = 6.67 x 10-34 J-s)

A car moving with a speed of 72kmph towards a hill.Car blows horn at a distance of 1800m from the hill.If echo is heard after 10s,the speed of sound (in ms-1) 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

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

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

Two tuning forks have frequencies 200 Hz and x. When they are sounded together 4 beats/sec heard. The value of x is

Dispersive power depends on the following :

A metal string is fixed between rigid supports. It is initially at negligible tension. Its youngs modulus is ‘Y’ density is ρ and coefficient of linear expansion is α. It is now cooled through a temperature ‘t’ transverse waves will move along it with a speed.

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

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.

A condenser 1μF is charged to a potential of 1000 volt. The energy stored in the condenser is:

A small amplitude progressive wave in a stretched string has a velocity of 10ms-1 and frequency of 100Hz.What is the phase differences, in radians between two points 5cm apart in the string?

In two separate collisions, the coefficient of restitutions e1 and e2 are in the ratio 3:1. In the first collision the relative velocity of approach is twice the relative velocity of separation, then the ratio between relative velocity of approach and the relative velocity of separation in the second collision is

A wooden block is dropped from the top of a cliff 100m high.Simultaneously a bullet of mass 10g is fired from the foor of the cliff upwards with a velocity of 100 m/s.The bullet and wooden block will meet each other after a time:

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

When a dielectric slab of the same area of cross-section and thickness equal to 2/3 of the separation is introduced between the plates of a parallel plate capacitor, its capacitance becomes 2.25 times the original value. The dielectric constant of the material of the slab 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

Match the appropriate pairs from Lists I and II: List-I List-II 1.NItrogen molecules A.continuous spectrum 2.Incandescent solids B.Absorption spectrum 3.Fraunhoffer lines C.Band spectrum 4.Electric arc between iron rods D.Emission spectrum

A pyknometer weight 40 g when empty and 1040 g when filled with mercury at 00C On heating to 1000C, 10 g of mercury overflows. If the coefficient of real expansion of mercury is 0.00020C the coefficient of expansion of glass is :

A car of mass 400 kg and travelling  at 72 kmph crashes into a truck of mass 4000 kg and travelling at 9 kmph, in the same direction. The car/bounces back at a speed of 18 kmph.The speed of truck after the impact is

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

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

A person is in between two vertical mountains.The person fires a gun then hears the first echo from the nearby mountain in a time 3s and hears second echo from far mountain in a time 4s.The person hears the third echo after

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

A flint glass prism is of refracting angle 50.Its refractive index for C line is 1.790 and for F line is 1.805.The angular dispersion of C and F lines is

Consider the following statements A and B and identify the correct answers given below :A : Peltier coefficient is numerically equal to the potential difference across the junctions of the thermocouple through which current is flowing.B : According to Thomson, energy is neither absorbed nor evolved at the junction of a thermocouple but is observed or evolved only along the lengths of both the conductors.

A stone is projected vertically up to reach maximum height h, The ratio of its kinetic energy to its potential energy, at a height (4/5) h, will be :

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

Frequency of tuning fork A is 250 Hz. It produces 4 beats/sec with another tuning fork B. When A is filed, the beat frequency is 6 beats/sec. The frequency of B is

In a coil of area 10cm2 and 10 turns with magnetic field directed perpendicular to the plane and is changing at the rate of 108 gauss/second.The resistance of the coil is 20Ω.The current in the coil will be

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

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

If a body is in equilibrium under a set of non-collinear forces, the minimum number of forces has to be

The lengths of two wires made of same material are 2m and 1m. Their radii are 1mm and 2mm. The ratio of their specific resistances 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

If c is velocity of light in fre space,the time taken by the light to travel a distance x in a medium of refractive index μ is given by:

A transistor having a β equal to 80 has a change in base current of 250μA,then the change in collector current 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 4Ω resistor in series with 8Ωresistance are connected to 12 V supply.If another resistor of 8Ω is connected across the 8Ω resistor the current drawn from source would be

The area of the coil in moving coil galvanometer is 80 cm2 and its has 200 turns. The magnetic induction of the radial field is 0.2T and the couple per unit twist of the suspension wire is 2 x 10-6Nm per degree. If the deflection is 40,the current passing through it is

A Tuning fork A produces 6 beats per second with another fork B.On loading B with a little wax,it produces 5 beats per second with A if the frequency of A is 256Hz,the frequency of B 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)

The potential energy of a proton is 3.2x10-18J at a particular point. The electric potential at this point 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

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

An inductance 1 H is connected in series with an AC source of 220 V and 50 Hz. The inductive reactance (in ohm) 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 :

The speed of transverse vibrations in a stretched string is 700cm/s.If the string is 2m long,the frequency with which it resonates in fundamental mode is

Two wires of same material and same length have their resistances in the ratio 5:7.The ratio of the masses of the wires is

The pair of physical quantities not having the same dimensional formula is :

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

The least distance of distinct vision is 25cm. If the focal length of convex lens is 10 cm. It acts as a simple microscope of maximum magnification

The equation of wave is y=10cos2π((t/0.02)-(x/10)),where ‘t’ is in seconds an x in cm.The phase difference between two points separated by a distance of 5cm at any instant 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

The crictical angle for light going from a medium in which wavelength is 4000A0 to medium in which wavelength is 6000A0

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

While connecting 6 cells in a battery in series,ina tape recorder,by mistake one cell is connected with reverse polarity.If the effective resistance of load is 24 ohm and internal resistance of each cell is one ohm and emf 1.5V,the current delivered by the battery is

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

Acurrent of 5Ais flowing through along straight copper wire.the ratio of the magnetic inductions at distance of 1.0 cm and 2.0cm from the is

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)

A double convex lens of focal length 30cm is made of glass of R.I.1.6. When it is immersed in a liquid, the focal length is found to be 90cm. The R.I of the liquid is

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 :

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:

In a prism, the effective indices of different colors are μv=1.6;μR=1.52;μr=1.56.The dispersive power of the prism is

The effect due to uniform magnetic field on a freely suspended magnetic needle is as follows :

A segment of wire vibrates with a fundamental frequency of 450 Hz under a tension of 9 kg wt. Then tension at which the fundamental frequency of the same wire becomes 900 Hz is

An ammeter whose resistance is 180 Ω shows full scale deflection when the current is 2mA.The shunt required to convert into an ammeter reading 20 mA is (in ohm)

A proton of mass m charge e is released from rest in a uniform electric field of strength E.The time taken by it to travel a distance d in the field is

A magnifying glass is made of a combination of convergent lens of power +20 diopters and a divergent lens of power -4 diopters .If the image is formed atleast distance of distinct vision (25cm), the magnifying power 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 bar magnet of 10 cm long is kept with its north (N)-pole pointing North. A neutral point is formed at a distance of 15 cm from each pole. Given the horizontal component of earth's field is 0.4 Gauss, the pole strength of the magnet is

A wire of length l having tension T and radius r vibrates with fundamental frequency f.Another wire of the same metal with length 2l having tension 2T and radius 2r will vibrate with fundamental frequency

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:

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

A particle of mass 4 m explodes into three pieces of masses m, m and 2 m. The equal masses move along X- and Y-axes with velocities 4 ms-1 and 6 ms-1 respectively. The magnitude of the velocity of the heavier mass is

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

The magnetic induction and the intensity of magnetic field inside an iron core of an electromagnet are 1 Wb m-2 and 150 Am-1 respectively. The relative permeability of iron is :(μ0=4π x 10-7 henry/m)

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

The direction of the magnetic field produced by straight current carrying conductor is given by

A given mass of a gas is compressed isothermally until its pressure is doubled. It is then allowed to expand adiabatically until its original volume is restored and its pressure is then found to be 0.75 of its initial pressure.The ratio of the specific heats of the gas is approximately

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 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

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:

A body of mass 5 kg makes an elastic collision with another body at rest and continues to move in the original direction after collision with a velocity equal to 1/10th  of its original velocity. Then the mass of the second body is

Two identical piano wires have a fundamental frequency of 600 c/s when kept under the same tension. What fractional increase in the tension of one wire will lead to the occurrence of 6 beats per second when both wires vibrate simultaneously      

In a metre bridge experiment, the ratio of the left gap resistance to right gap resistance is 2 : 3, the balance point from left is

Two tuning forks A and B give 6 beats per second .A resonates with a closed column of air 15 cm long and B with an open column 30.5 cm long in their fundamental harmonics.Their frequencies are

Keeping the banking angle sam,to increase the maximum speed with which a vehicle can travel on a curved road by 10 percent the radius of curvature of the road has to be changed from 20m to :

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 sonometer wire produces 2 beats per second with a tuning fork, when the length of the wire is either 102cm or 1004cm.The frequency of the tuning fork 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

In a thermo couple the cold junction is at 300C.The temperature of inversion is found to be 5400C,Then the neutral temperature 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

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

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

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

Identify the increasing order of the angular velocities of the following :1.earth rotating about its own axis2.hour's hand of a clock3.second's hand of a clock4.flywheel of radius 2 m making 300 rpm

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 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 :