A to Z Exams

Δλ is the difference between the wave length of kα line and the minimum wavelength of the continuous X-ray spectrum when the X-ray tube is operated at a voltage V. If the operating voltage is changed to v/3 , then the above difference is Δλ'. Then :

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 :

Emission of electrons in photoelectric effect is possible if :

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:

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 fundamental frequency of a sonometer wire is 200 Hz when a body whose relative density 4 is suspended at the end of wire.The fundamental frequency of the same wire when the suspended body is made to immerse in water is

Electric charges of 1μC, 1 μC and 2 μC are placed in air at the corners of A, B and C respectively of an equilateral triangle ABC having the length of the side 10 cm.The resultant force at C is (1/(4πε0 = 9 x 109 N-m2/ c2

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

Which of the following is more effective in inducing nuclear fission ?

A transformer steps up an A.C. voltage from 230V to 2300V. If the number of turns in the secondary coil is 1000, the number of turns in the primary coil will be

Two lenses of focal lengths +10cm, and -15cm when put in contact behave like a convex lens .They will have zero longitudinal chromatic aberration if their dispersive powers are in the ratio

A bullet of mass 0.02 kg travelling horizontally with velocity 250 ms_1 strikes a block of wood of mass 0.23 kg which rests on a rough horizontal surface. After the impact, the block and bullet move together and come to rest after traveling a distance of 40 m. The coefficient of sliding friction of the rough surface is

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)

The distances between the objective and the eye lens of an astronomical telescope when adjusted for parallel light is 100cm.The measured value of the magnification is 19.The focal length of objective and eye piece are

(A): bending of a conducting wire effects electrical resistance (R): Resistance of a wire depends on resistivity of that material

A body projected vertically upwards crosses a point twice in its journey at a height h just after t1 and t2 seconds. Maximum height reached by the body is

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

Two vibrating tuning forks produce vibrations at the tympanic of an observer represented by y1=4sin(260 πt) and y2=4sin(256 πt).The number of beats heard by the observer in one minute 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

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 :

The elementary particles heavier than nucleons are called

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

Two particles P and Q are located at distance rp and rq respectively from the centre of a rotating disc such that rp > rq

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 tuning fork A of frequency 384Hz produces 3 beats/second when sounded with a second tuning fork B of unknown frequency.When a is filed a little,the number of beats decreased to 2 beats/second.The frequency of the fork B must be

The half life of Ra226 is 1620 years. Then the number of atoms decay in one second in 1 gm of radium (Avogadro number = 6.023x1023)

A free neutron decays spontaneously into :

Two electric charges 12 μC and -6 μC are placed 20 cm apart in air, there will be a point P at which electric potential is zero outside excluding the region between them. The distance of P from -6 μC charge is:

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

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

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 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 :

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

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:

A liquid of mass m and specific heat S is heated to a temperature T. Another liquid of mass mil and specific heat 2 S is heated to temperature 2 T. If these two liquids are mixed, the resultant temperature of the mixture :

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

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

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

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 source producing sound of frequency 170 Hz is approaching a stationary observer with a velocity of 17 ms-1. The apparent change in the wavelength of sound heard by the observer is: (speed of sound in air=340ms-1)

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 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

If the angle of minimum deviation produced by equilateral prism is 300.The refractive index of the prism is

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

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 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 auditorium has volume of 105m3 and surface area of absorption 2 x 104m2.Its average absorption coefficient is 0.2 .The reverberation time of the auditorium in seconds is

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

When an air column of length ‘l’ open at both ends vibrates in its fundamental note, the wavelength is given by

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:

X-rays of energy 50 KeV are scattered from a carbon target. The scattered rays are detected at 900 from the incident beam. the percentage change in wave length approximately [mo=9.0x10-31kg, c=3x108 m/sec] is

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

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 :

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

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)

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

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 force of 5 N making an angle 8 with the horizontal acting on an object displaces it by 0.4 m along the horizontal direction. If the object gains kinetic energy of 1 J the horizontal component of the force is :

7N14+2He4→X+1H1 then ‘X’ 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

Neutral temperature of a thermo couple is 2500C.If the value of’a’ is 15μv/0C,the value of ‘b’ is

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

A whistling engine is approaching a stationary observer with a velocity of 110m/s. The velocity of sound is 330m/s. The ratio of frequencies as heard by the observer as the engine approaches and recedes 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):

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

S.I unit of electrical conductivity

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

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

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

An electrical meter of internal resistance 20Ω gives full scale deflection when one milliampere current flows through it.The maximum current that can be measured by using three resistors of resistance 12Ω each,in milliamperes 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.

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

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      

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 1.5 m is

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

The coils in two moving coil galvanometer have their areas in the ratio of 2:3 and number of turns in the ratio 4:5. These two coils carry the same current and are situated in the same field. The deflections produced by these coil will be in the ratio of

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 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

Two charges 2C and 6C are separated by a finite distance. If a charge of -4C is added to each of them, the initial force of 12 x 103 N will change to

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 :

A tension of 22 N is applied to a copper wire of cross-sectional area 0.02 cm2 Young’s modulus of copper is 1.1x1011 N/m2and Poisson’s ratio 0.32. The decrease in cross sectional area will be

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 :

In a Ramsden eyepiece of effective focal length 3 cm the focal length of eye lens, in cm, is :

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

The waves are represented by the following equations y1=5 sin 2π(10t-0.1x),y2=10 sin 2π(20t-0.2x)ratio of intensities l2/l1 will be

In a full wave rectifier output is taken across a load resistor of 800ohm.If the resistance of diode in forward biased condition is 200 ohm,the efficiency of reflection of rectification of ac power into dc power 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

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

Consider the following statements A and B and identify the correct answer :(A) : In an elastic collision, if a body suffers a head on collision with another of same mass atrest, the first body comes to rest while the other starts moving with the velocity of the first one.(B) : Two bodies of equal mass suffering a head on elastic collision merely exchanges their velcities :

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 :

Two tuning forks of frequencies 250 and 256 Hz produce beats. If maximum is produced now, thus the minimum time after which minimum is produced at that same place

The frequency of the sound of a car horn as recorded by an observer towards whom the car is moving differs from the horn by 10%. Assuming the velocity of sound in air to be 330ms-1, the velocity of the car is

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

A charge of 10 units is divided so that force between the two charges is maximum when placed 2cm apart. The two charges are

A simple microscope is rated 5x for a normal relaxed eye.what will be its magnifying power for a far sighted man whose near point is 40 cm.

In an experiment of photoelectric emission, for incident light of 4000A0, stopping potential is 2V. If the wavelength of incident light is made 3000A0, then the stopping potential will be

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

If the magnitude of the intensity of a magnetic field at a distance x on the axial line and at a distance y on the equatorial line of a given dipole have the same value the ratio x : y is :