A to Z Exams

Two bar magnets A, B are placed one over the other and are allowed to vibrate in a vibration magnetometer. They make 20 oscillations per minute when the similar poles of A and B are on the same side, while they make 15 oscillations per minute when their opposite poles lie on the same side. If MA and MB are the magnetic moments of A and B and if MA > MB, the ratio of MA and MB is

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

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

The coils A and B having the radii in the ratio 1:2 carrying currents in the ratio 5:1 and have the number of turns in the ratio 1:5.The ratio of magnetic inductions at their centres is

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 area of the coil in moving coil galvanometer is 80 cm2 and its has 200 turns. The magnetic induction of the radial field is 0.2T and the couple per unit twist of the suspension wire is 2 x 10-6Nm per degree. If the deflection is 40,the current passing through it is

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

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 :

Two ions having masses in the ratio 1:1 and charges 1 : 2 are projected into uniform magnetic field perpendicular to the field with speeds in the ratio 2:3. The ratio of the radii of circular paths along with the two particles move is

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

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 proton is projected with a velocity 107ms-1 ,at right angles to a uniform magnetic field of induction 100mT.The time(in seconds)taken by the proton to traverse 900 arc is:(Mass of proton=1.65x10-27kg and charge of proton = 1.6x10-19C

The direction of the magnetic field produced by straight current carrying conductor is given by

Which one of the following statement is true ?

When a positively charged particle enters a uniform magnetic field with uniform velocity, its trajectory can be : 1) a straight line 2) a circle 3) a helix

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 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

Two long straight conductors are held parallel to each other at a distance 0.3 m. If the conductors carry currents 2A and 8A in opposite directions, the distance of the neutral point from the conductor carrying smaller current is:

A long straight wire carries an electric current of 2A.The magnetic induction at a perpendicular distance of 5m from the wire is (μ0=4πx10-7 Hm-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 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

An electron beam travels with a velocity of 1.6 x 107 ms-1 perpendicularly to magnetic field of intensity 0.1 T. The radius of the path of the electron beam (me = 9 x 10-31 kg)

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 :

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

A long horizontal rigidly supported wire carries ia=96A.Directly above it and parallel to it at a distance, another wire of 0.144N weight per meter carrying a current ib=24A, in a direction opposite to that of ia is placed. If the upper wire is to float in air due to magnetic repulsion, then tits distance (in mm) from the lower wire is:

A proton takes 10-12 to complete one revolution in uniform magnetic field.The time taken in another orbit of double the radius in the same field 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 coil of radius π meters,100 turns carries a current of 3A.The magnetic induction at a point on its axis at a distance equal to √3 times its radius from its centre is

A wire carrying a current of 140 ampere is bent into the form of a circle of radius 6cm.The flux density at a distance of 8 cm on the axis passing through the centre of the coil and perpendicular to its plane is(in wb/m2(approximately))

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)