A to Z Exams

The objective of a telescope has focal length 120cma and diameter 5cm.The focal length of the eye piece is 2cm.The magnifying power of the telescope for distant object 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 :

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 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

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

The displacement of a particle executing SHM is given by  y = 5 sin (4t +  π/3 ) of T is the time period and the mass of the particle is 2 gms, the kinetic energy of the particle when t  = T/4 is given by

Two tuning forks A and B produce 6 beats per second when sounded together. When B is slightly loaded with wax the beats are reduced to 4 per second. If the frequency of A is 512 Hz the frequency of B is

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

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):

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

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)

Particles and their anti-particles have

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

Which one of the following statement is true ?

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

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

The machine gun fires 240 bullets per minute. If the mass of each bullet is 10 g and the velocity of the bullets is 600 ms-1, the power (in kW) of the gun is :

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

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

The displacement of a particle moving in a straight line is given by x = 2t2+t+5 where x is expressed in meter and 't' in second.The acceleration at t = 2sec is

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)

Three unequal resistors in parallel are equivalent to a resistance 1 ohm. If two of them are in the ratio 1:2and if no resistance value is fractional the largest of the three resistances in ohms 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:

A gun is aimed at a target in line with its barrel. The target is released and allowed to fall under gravity, at the instant, the gun is fired. The bullet will :

A transverse wave propagating on a stretched string of linear density 3x10-4kgm-1 is represented by the equation y=0.2sin(1.5x+60t) where x is in meter and t is in seconds. The tension in the string in N.

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

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

If Foucoult's method for determining the velocity of light in air, the distance between the concave mirror and the rotating mirror was 5 km. The speed of rotation of the rotating mirror was 300 revolutions per second. If the reflected ray is displaced through π/60 radian, the velocity of light in air is :

A bucket filled with water is tied to a rope of length 0.5 m and is rotated in a circular path in vertical plane. The least velocity it should have at the lowest point of circle so that water doesnot spill is, (g = 10 ms-2 )

A body of mass m is suspended to an ideal spring of force constant k. The expected change in the position of the body due to an additional force F acting vertically downwards is

Photoelectric current can be increased by using :

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)

In an electric motor,wires carrying a current of 5A are placed at right angles to magnetic field of induction 0.8T.If each wire has length of 20cm,then the force acting on each wire

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

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)

The following phenomenon which is not explained by Huygens construction of wave front is

If the earth suddenly stops rotating, the value of g at equator would :

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

An observer to moving away from a source of sound of frequency 100 Hz at a speed of 33 m/s. If the speed of the sound in air is 330 m/s and the observed frequency is

The radioactivity of a sample is 'X' at a time 't1' and ‘Y’ at a time 't2'. If the mean life time of the specimen is г the number of atoms that have disintegrated in the time interval (t1 – t2) is

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

A body of weight "64N" is pushed with just enough force to start it moving across a horizontal floor and the same force continues to act afterwards, if the coefficients of static and dynamic friction are 0.6 and 0.4 respectively, the acceleration of the body is: (acceleration due to gravity = g)

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

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

Consider the two following statements A and B,and identify the correct choice given in the answers:A) In photovoltaic cells the photoelectric current produced is not proportional to the Intensity of Incident light (B) In gas filled photo emissive cells, the velocity of photo-electrons depends on the wavelength of the incident radiation

Two cylinders A and B fitted with pistons, contain equal number of moles of an ideal mono atomic gas at 400 K. The piston of A is free to move while that of B is held fixed. Same amount of heat energy is given to the gas in each cylinder. If the rise in temperature of the gas in A is 42 K, the rise in temperature of thegas in B is (γ = 5/3)

If the cold junction is held at 00C, the same thermo emf V of a thermocouple varies as V = 10 x 10 6t - * x 10 bt2, where t is the 40 temperature of the hot junction in 0C. The neutral temperature and the maximum value of thermo emf are respectively:

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 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

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

Two cylindrical conductors A and B of same metallic material have their diameters in the ratio 1 : 2 and lengths in the ratio 2 : 1. If the temperature difference between their ends is same, the ratio of heats conducted respectively by A and B per sec is:

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 )

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

Fraunhofer lines are produced by the absorption of light in :

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 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

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 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

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]

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

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

The difference between volume and pressure coefficients of an ideal gas 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 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 :

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 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 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 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

Two cells A and B are connected in the secondary circuit of a potentiometer one at a time and the balancing length are respectively 400 cm and 440 cm. The emf of the cell A is 1.08 volt. The emf of the second cell B in volts 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:

In Huygen's eyepiece

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 bar magnet of magnetic moment M and moment of inertia I is freely suspended such that the magnetic axial line is in the direction of magnetic meridian. If the magnet is displaced by a very small angle (θ), the angular acceleration is (Magnetic induction of earth's horizontal field = BH)

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

A radioactive sample has half life of 5 days. To decay from 8 micro-curies to 1 micro-curie, the number of days taken will be :

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

A tuning fork is in resonance with a sonometer wire. The same tuning fork produces 3 beats in 2s, when tension in the wire is increased by 2% . The frequency of wire before increasing tension 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

An infinitely long thin straight wire has uniform linear charge density of 1/3 coul.m-1.Then the magnitude of the electric intensity at a point 18 cm away 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)

Emission of electrons in photoelectric effect is possible if :

In Ramsden eyepiece, the two planoconvex lenses each of focal length / are separated by a distance 12 cm. The equivalent focal length (in cm) of the eyepiece 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

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

A condenser of 20μF is charged to a certain voltage and then discharged through a 4x106Ω resistor.The time taken for the condenser to lose 63% of its charge 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

Two concentric circular coils A and B have radii 25cm and 15cm and carry currents 10A and 15A respectively.A has 24 turns and B has 18 turns.The direction of currents are in opposite order.The magnetic induction at the common centre of the coil 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 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 25 watt,220 volt bulb and a 100 watt,220 volt bulb are connected in series across 440 volt line

A first order reaction has commenced with 0.2M solution of the reactants. If the molarity of the solution falls to 0.02M after 100 minutes the rate constant of the reaction is

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,

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

The total mechanical energy of a harmonic oscillator of A=1m and force constant 200 N/m is 150J.Then

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)

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:

A capacitor of capacity C is charged to a potential V.It is charged and isolated.Then distance between the plates is halved and then half the distance between them is filled with a metal slab.Then the capacitor

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 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