A to Z Exams

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 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)

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

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

A 100 PFcapacitor is charged to a potential difference of 24V.It is connected to an uncharged capacitor 20PF.what will be the new potential difference across 100PF capacitor

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

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)

In order to double the frequency of the fundamental note emitted by a stretched string, the length is reduced to 3/4th of the original length and the tension is changed. The factor by which the tension is to be changed is:

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

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

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

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)

Three point charges 1C, -2C and -2C are placed at the vertices of an equilateral triangle triangle of side 1 metre The work done by an external force to increase the separation of the charges to 2 metre in joule is : (ε0= permittivity of air)

Two straight parallel wires carry currents of 200mA and 1A in opposite directions.If the wires are 20 cm apart,the distance of the neutral point from the 1A wire is(in cm) ±

The equation connecting thermo emf with the temperature difference between the junctions 't' of a thermocouple, whose cold junction is maintained at 00C, is given by e = 2040 t - 6.2 t2. The neutral and inversion temperatures of the thermocouple in C .ire respectively and nearly equal to:

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

One mole of a gas occupies 100 ml at 50 mm pressure.The volume of 2 mole of the gas at 100 mm pressure and same temperature is

The cold junction of a thermocouple is at 00 C,The thermo e.m.f produced in the thermocouple is given by the equation E=16T-0.04T2V , where T is the temperature of the hot junction.The temperature of inversion and neutral temperature of the thermo couple are

The locus of the centre of a circle which cuts the circles 2x2+2y2-x-7=0 and 4x2+4y2-3x-y=0 orthogonally is a straight line whose slope is

The emf of a Cu-Fe thermocouple varies with the temperature T of the hot junction, the cold junction being at 100C, as Vinμv=14T-0.02T2.Determinate the neutral temperature and the of inversion.

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)

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

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

A pipe having an internal diameter ‘D’ is connected to anther pipe of same size. water flows into the second pope through ‘n’ holes, each of diameter ‘d’. If the water in the first pipe has speed ‘V’, the speed of water leaving the second pipe 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

A ball ‘A’of mass ‘m’ moving along positive x-direction with kinetic energy ‘K’ and momentum P undergoes elastic head on collision with a stationary ball B of mass ‘M’ After collision the ball A moves along negative X-direction with kinetic energy K/9,Final momentum of B 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.

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 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

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

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

Calculate enthalpy for formation of ethylene from the following dataI. C(graphite)  + O2(g) ----->  CO2(g)   ∆H = 393.5kjII. H2(g) + (1/2) O2(g) ---------->  H2O(l) ∆H = -286.2kjIII.C2H4(g) + 3O2(g) ----------> 2CO2(g) + 2H2O(l)   ∆H = -1410.8kj

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 and consider fundamental frequencies)

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.

The energy stored in a capacitor is given by (V = voltage, C = capacitance. q= charge)

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 :

When a liquid is heated in copper vessel its Coefficient of apparent expansion is 6x10-6/0C.When the same liquid is heated in a steel vessel its coefficient of apparent expansion is 24x10-6/0C If coefficient of linear expansion for copper is 18x10-6/0C the coefficient of linear expansion for steel is

A 2 kg mass moving on a smooth frictioriless surface with a velocity of 10 m/s, hits another 2 kg mass kept at rest in an elastic collision. After collision, if they move together:

Two charges 8C and -6C are placed at a distance of separation d between them and exerts a force of magnitude  F on each other. If a charge 8C is added to each of these and they are brought nearer to by a distance d/3, the magnitude of force between them

The frequency of a stretched uniform wire under tension is in resonance with the fundamental frequency of a closed tube.If the tension in the wire is increased by 8N, it is in resonance with first overtone of the closed tube.The initial tension in the wire 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)

A. ball of mass m moving with a velocity V*collides head on elastically with another of the same mass m but moving with a - V  (in the opposite direction). After the collision :

The magnitude of the force between parallel conductors, each of length 110 cm,carrying a current of 10A and separated by a distance of 10 cm is

The elementary particles heavier than nucleons are called

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

Work done by 0.1 mole of gas at 270C when it expands to double its volume at constant pressure is : (assume R = 2 cal/mol-1 K-1)

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

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 :

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)

An iron sphere of mass 20 x 10-3 kg falls through a viscous liquid with terminal velocity 0.5 ms-1. The terminal velocity (in ms-1) of another iron sphere of mass 54 X 10-2 kg 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

A cell of emf e1 in the secondary circuit gives null deflection for1.5m length of potentiometer of wire length 10m.If another cell of emf e2 is connected in series with e1 then null reflection was obtained for 2.5 m length.Then e1:e2

The charge stored in a capacitor is 20μC and the potential difference across the plates is 500V,its capacity is

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

The weight of a man in a lift moving upwards is 608 N while the weight of the same man in the lift moving downwards, with the same acceleration is 368 N. His normal weight in N is:

A wire stretches by 0.01 m when it is stretched by a certain force.Another wire of the same material but double the length and double the diameter is stretched by the same force.The elongation 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

An insulated cylindrical vessel filled with an insulated piston of negligible weight and negligible thickness at the midpoint of the vessel. The cylinder contains a gas at 0oC. When the gas is heated to 100oC, the piston moves through a length of 5 cm. Length of the cylindrical vessel in cm 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?

A train is travelling at 120kmph and blows a whistle of frequency 1000Hz.The frequency of the note heard by a stationary observer if the train is approaching him and moving away from him are(Velocity of sound in air=330ms-1)nearly

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

When two capacitors are joined in series the resultant capacity is 2.4 μF and when the same two are joined in parallel the resultant capacity is 10μF.their individual capacities are

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 condenser of capacity 10μF is charged to a potential of 500V. Its terminals are then connected to those of an uncharged condenser of capacity 40μF. The loss of energy in connecting them together 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

Two organ(open)pipes of lengths 50cm and 51cm produce 6 beats/s.Then the speed of sound is nearly

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

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

in a half wave rectifier output is taken across a 90 ohm load resistor. If the resistance of diode in forward biased condition is 10 ohm, the efficiency o rectification of ac power into dc power is

The energy stored in a sphere of 10cm radius when the sphere is charged to a potential of 300 volt 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 1.5 m 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 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

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

Two small angled prisms A and B deviate the blue rays by 70 and 90 and the red rays by 50 and 70 respectively. The prism which has a greater dispersive power is

In n-p-n transistor, in CE configuration:(1)  The emitter is heavily doped than the collector.(2)  Emitter and collector can be interchanged.(3)  The base region is very thin but is heavily doped.(4)  The conventional current flows from base to emitter

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

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 :

The photoelectric work function of a metal surface is 2eV.When light of frequency 1.5x1015Hz is incident on it,the maximum kinetic energy of the photo electrons approximately 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

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

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 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

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

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

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 magnitude of maximum acceleration is π times that of maximum velocity of a simple harmonic oscillator. The time period of the oscillator in seconds is

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

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 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

The velocity of propagation of sound is 330 m/s, in air. If the third harmonic of the fundamental that can be exerted in an open ended tube is 450 Hz, the length of the tube is :

Two very wide parallel glass plates are held vertically at a small separation r,and dipped in water surface tension S.Some water climbs up in the gap between the plates. If P0 is the atmospheric pressure of water just below the water surface in the region between the two plates is

In Millikans oil drop experiment, an oil drop of radius r charge q falls under the gravity with a terminal velocity Vg and moves up with a terminal velocity Ve in the uniform vertical electric field of intensity E. If η is coefficient of viscosity of air, the charge of oil drop is

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 sources A and B are sending notes of frequency 680 Hz. A listener moves from A to B with a constant velocity V. If the speed of sound in air is 340 ms-1, what must be the value of V so that he hears 10 beats per second