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If λ_{0} is the deBroglie wavelength for a proton accelerated through a potetial difference of 100 V, the deBroglie wavelength for α particle accelerated through the same potential difference is
The number of dry cells, each of e.m.f. 1.5 volt and internal resistance 0.5 ohm that must be joined in series with a resistance of 20 ohm so as to send a current of 0.6 ampere through the circuit is
The resistance of a coil is 4.2 Ω at 100ºC and the temperature coefficient of resistance of its material is 0.004/ºC. Its resistance at 0ºC is
A body of mass 0.05kg is observed to fall with an acceleration of 9.5ms^{2}. The opposing force of air on the body is........(g = 9.8ms^{2})
The electric field inside a charged conductor of radius r is
Power delivered by the source in the circuit is maximum, when
Acceleration due to gravity is 'g' on the surface of the earth. The value of acceleration due to gravity at a height of 32 km above earth's surface is
Two identical conducting plates of plate area A are separated by a distance d to form a parallel plate air capacitor. Now a metal sheet of thickness d/2 is inserted between the plates of the capacitor. The ratio of capacitance before the insertion of plate and after the insertion of plate is
Now capacitance of capacitor before inserting metal plate is
C = (ε_{0}A)/d
And after the insertion of any dielectric plate filling the capacitor partially is
C = (ε_{0}A)/[(dt)+t/K]
We know that K for a metal is infinite thus
C = (ε_{0}A)/(dt) Here t=d/2
thus C’=(2ε_{0}A)/d=2C
C:C’=1:2
Hence (a) is the correct choice
A galvanometer has a resistance of 25 Ω and a maximum of 0.01 A current can be passed through it. In order to change it into an ammeter of range 10 A, the shunt resistance required is
To convert a galvanometer into a voltmeter, we must connect a
At the neutral point, horizontal component of the magnetic field due to a magnet is
A car moves for half of its time at 80 km/h and for rest half of time at 40 km/h. Total distance covered is 60 km. What is the average speed of the car?
A stone is just released from the window of a train moving along a horizontal straight track. The stone will hit the ground following
A cricketer can throw a ball to a maximum horizontal distance of 100 m. The speed with which he throws the ball is (to the nearest integer)
Among electron, proton, neutron and α  particle the maximum penetration capacity is for
A mass m is vertically suspended from a spring of negligible mass. The system oscillates with a frequency n. What will be the frequency of the system, if a mass 4m is suspended from the same spring ?
A spring has a certain mass suspended from it and its period for vertical oscillation is T. The spring is now cut into two halves and the same mass is suspended from one of the halves. The period of verticle oscillation is now
A circular disc is to be made by using iron aluminium, so that it acquires maximum moment of inertia about its geometrical axis. It can be obtained with
A ray of light is incident on a surface of glass slab at an angle 45^{0} . If the lateral shift produced per unit thickness is the angle of refraction produced is
Platinum and silicon are heated upto 250ºC and after then cooled. In the process of cooling
70 calories of heat are required to raise the temperature of 2 moles of an ideal gas at constant pressure from 30ºC to 35ºC. The amount of heat required to raise the temperature of the same sample of the gas through the same range at constant volume is nearly (Gas constant = 1.99 cal/Kmole)
Which of the following pair of physical quantities had same dimensional formula?
Who was the first to demonstrate the phenomenon of interference of light?
The circuit shown in the figure contains two diodes each with a forward resistance of 50 ohms and with infinite backward resistance .If the battery voltage is 6V, the current through the 100 ohm resistance (in amperes) is
A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is propotional to
The pulleys and strings shown in the figure are smooth and of negligible mass, For the system to remain in equilibrium the angle θ should be
The north pole of a magnet is brought near a metallic ring .The direction of induced current in the ring will be
Correct option is
a
Anticlockwise
When we bring a north pole near a metallic ring applying Lenz's law the ring will behave as north pole so that repulsion occurs. So direction ofcurrent induced in it will be anticlockwiseas depicted above.
A point source of light of power P and wavelength λ is emitting light in all direction. The number of photons present in a spherical region of radius r to radius 2r with centre at source, is
If the same instrument is to measure 25 V, the resistance to be connected in series is
A conducting square loop of the side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic induction constant in time and space, pointing perpendicular and into the plane of the loop exists everywhere. The current induced in the loop is
A shell is fired from a cannon with a velocity v (m/sec.) at an angle θ with the horizontal direction. At the highest point in its path it explodes into two pieces of equal mass. One of the pieces retraces its path to the cannon and the speed (in m/sec) of the other piece immediately after the explosion is
A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth.
Two very long, straight, parallel wires carry steady currents I and I respectively. The distance between the wires is d. At a certain instant of time, a point charge q is at a point equidistant from the two wires, in the plane of the wires. Its instantaneous velocity is perpendicular to this plane. The magnitude of the force due to the magnetic field acting on the charge at this instant is
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