A to Z Exams

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 :

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

Two tangent galvanometers are connected in series across a battery.The deflection in them are found to be 300 and 600 respectively.The ratio of their reduction factors respectively 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

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

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

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

Electrons ejected from the surface of a metal, when light of certain frequency is incident on it, are stopped fully by a retarding potential of 3 volts. Photoelectric effect in this metallic surface begins at a frequency 6 x 1014s-1. The frequency of the incident light in s-1is : [ Planck's constant = 6.4 x 10-34Js, charge on the electron = 1.6 x 10-19C]

The elementary particles heavier than nucleons are called

When a dielectric material is introduced between the plates of a charged condenser the  electric field between the plates:

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

The spheres of different materials one with double the radius and one-fourth wall thickness of the other are filled with ice.If the time taken for complete melting of ice in the larger radius one is 25 minutes and that for smaller one is 25 minutes,the ratio of thermal conductivities of materials of larger sphere to smaller sphere is:

In Young’s double slit experiment,the intensity at appoint P on the screen is half the maximum intensity in the interference pattern.If the wavelength of light used is λ and d is the distance between the slits, the angular separation between point P and the center of the screen is

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

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)

A galvanometer of resistance 20Ω is to be shunted so that only 1% of the current passes through it. Shunt connected is

A vessel is filled with an ideal gas at a pressure of 10 atmosphere and temperature 270C. Half of the mass of the gas is removed from the vessel and temperature of the remaining gas is increased to 870C.Then the pressure of the gas in the vessel will be

Two charges each of 100 micro coulomb are separated in a medium of relative permittivity 2 by a distance of 5cm.The force between them 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

The fundamental physical quantities that have same dimensions in the dimensional formula of torque and angular momentum are

The mass of a planet is half that of the earth and the radius of the planet is one-fourth that of earth. If we plan to send an artificial satellite from the planet, the escape velocity will be, (escape velocity on earth ve =11 km- s-1)

Two metal rods A and B of equal lengths and equal cross-sectional areas are joined end to end. The coefficients of thermal conductivities of A and B are in the ratio 2 : 3, when the free end of A is maintained at 1000C and the free end of B is maintained at 00C, the temperature of the junction is

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 :

The velocity v (in cm/sec) of a particle is given in terms of time t (in sec) by the equation,V = at + [b / (t+c)]. The dimensions of a,b,c are

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)

Two solid spheres A and B made of the same material have radii rA and rB respectively. Both the spheres are cooled from the same temperature under the conditions valid for Newton's law of cooling. The ratio of the rate of change of temperature of A and B 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 electric current passes through a long straight wire. At a distance 5cm from the wire, the magnetic field is B. The field at 20cm from the wire would be:

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 ball is projected vertically down with an initial velocity from a height of 20 m on to a horizontal floor. During the impact it loses 50% of the energy and rebounds to the same height, the initial velocity of its projection 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)

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 length of an elastic string is 'a' metres when the longitudinal tension is 4 N and 'b' meters when the longitudinal tension is 5 N. The length of the string in metres when the longitudinal tension is 9 N is:

In youngs experiment λ=4000A0 fringes observed have a width β. The light illuminating with new λ=6000A0 and the separation between the interfering sources is halved. The ratio of the distance between the screen and the interfering sources if the fringe width remains unaltered respectively 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

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

The tyre of a motor car contains air at 150C. If the temperature increases to 350C, the approximate percentage increase in pressure is (ignore to expansion of tyre)

A sphere of radius 1m encloses a charge of 5μC. Another charge of -5μC is placed inside the sphere. The net electric flux would be

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)

In Young's double slit experiment, the 10th maximum of wavelength λ1 is at a distance of y1 from the central maximum. When the wavelength of the source is changed to λ2, 5th maximum is at a distance of y2 from its central maximum. then the ratio of y1 / y2 is

Consider a p-n junction as a capacitor, formed with p nnd n-materials acting as thin metal electrodes and depletion layer width acting as separation between them. Basing on this, assume that a n-p-n transistor is working as an amplifier in CE configuration. If C1 and C2 are the base-emitter and collector-emitter junction capacitances , then :

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

A charged particle of mass 3 x 10-6 held stationary in spacing in an electric field of strength 106 NC-1 directed vertically downwards. The charge on the particle 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

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 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

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 :

In Huygen's eyepiece

A galvanometer of resistance 20Ω is to be shunted so that only 1% of the current passes through it.shunt connected is

A train is moving towards north with a speed of 180 kilometers per hour. If the vertical component of the earths magnetic field is 0.2x10-4T, the emf induced in the axle of length 1.5m is

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

The dispersive powers of the materials of two lenses forming an achromatic combination are in the ratio of 4:3. Effective focal length of the two lenses is +60 cm then the focal lengths of the lenses should be

While a collector to emitter voltage is constant in a transistor, the collector current changes by 8.2 mA. When the emitter current changes by 8.3 mA. The value of forward current ratio is:

Four resistors A,B,C and D form a Wheatstones bridge. The bridge is balanced when C = 100Ω .If A and B are interchanged, the bridge balances for C= 121Ω.The value of D is

A juggler maintains four balls on motion, making each inturn rise to a height 20m from his hand. Where will the other three balls be at the instant when the fourth one is just leaving the hand?

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

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)

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

The difference between heats of reaction at constant pressure and at constant volume for the reaction 2C6H6(l)+15O2(g) → 12CO2(g)+6H2O(l) at 250C in KJ 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

A train approaching a level crossing at a speed of 20m/s sounds a horn of frequency 628Hz when 80m form the crossing.A person is standing at 60m from the level crossing on a road which is perpendicular to the railway track.Then the apparent frequency heard by the person is (velocity of sound in air is 330m/s)

S.I unit of electrical conductivity

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

If the critical angle of medium is 300. Then the polarizing angle for that medium is

A bomb is dropped from an aircraft travelling horizontally at 150m/s at a height of 490m. The horizontal distance travelled by the bomb before it hits the ground is (in metre):

The ratio of effective focal length of Huygens eye piece and the object distance of its field lens is

Magnetic field induction at the centre of a circular coil of radius 5 cm and carrying a current 0.9 A is (in S.I. units) (ε0 = absolute permittivity of air in S.I. units; velocity of light = 3 x 108 ms-1)

A thin magnetic iron rod of lenght 30cm is suspended in a uniform magnetic filed.Its time period of oscillation is $s.It is broken into three equal parts.The time period in seconds of oscialltion of one part when suspended in the same magnetic filed 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

A cell of emf 2V and negligible resistance is connected in series with a resistance of 5 Ω, and a potentiometer wire of resistance 10 ohm. What is the potential drop per cm if the length of the potentiometer wire is 10 m. The emf a cell which is balanced by 750 cm long wire is

A small square loop of wire of side l is placed inside a large square loop of side L(L>>1). If the loops are coplanar and their centres coincide, the mutual induction of the system is directlv proportional to :

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 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

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

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

A sonometer is set on the floor of a lift. When the lift is at rest, the sonometre 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

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      

The loss of weight of a solid when immersed in a liquid at 00C is .If α and β are the volume coefficients of the solid and the respectively, then the loss of weight at C is approximately

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

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

The wavelength of blue light in air is 45000A if the refractive index for blue light is 1.55 in glass what will be the wavelength of blue light in glass(c=3x108m/s)its frequency is

A cell in secondary circuit gives null deflection for 2.5 m length of potentiometer having 10 m length of wire If the length of the potentiometer wire is increased by 1 m without changing the cell in the primary, the position of the null point now is

The frequency of a tuning fork A is 2% greater than that of standard fork K.The frequency of another tuning fork B is 3% less than K.When A and B are vibrated together 6 beats per second are heard per second. The frequencies of A and B are

A varying current in a coil changes from 10 A to zero in 0.5 seconds. If the average emf induced in the coil is 220 volts, the self-inductance of the coil is:

In a chemical reaction, ΔH=150KJ and ΔS=100JK-1 at 300K. ΔG would be

For the system S(s)+O2(g)→SO2(g)?

A long string with a charge of λ per unit length passes through an imaginary cube of edge a. The maximum flux of the electric field through the cube will be

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

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

A clock pendulum made of invar has a period of 0.5 s , at 200 C . If the clock is used in a climate where the temperature averages to 300 C how much time does the clock loose in each oscillation (for invar α = 9 x 10-70 C and g = constant

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

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

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

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 flask is filled with 1.3 g of an ideal gas at 270C and its temperature is raised to 520C The mass of the gas that has to be released to maintain the temperature of the gas in the flask at 520C and the pressure remaining the same is

Photons of energy 2.0 eV and wavelength λ fall on a metal plate and release photoelectrons with a maximum velocity v.By decreasing X by 25% the maximum velocity of photoelectrons is doubled. The work function of the material of the metal plate,in eV is:

A coil of 50 turns has dimension 10 x 10 cm. It is roated at the rate of 5 rps in a uniform magnetic field of flux density 0.7T. The maximum emf included in it 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:

A black body radiates energy at the rate of E watt/m2 at a high temperature T K. When the temperature is reduced to (T/2) K, the radiant energy is

A motor car approaching a cliff with velocity of 90Kmph soundsthe 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