A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed is both the cases, then the ratio of the magnetic induction at their centers will be

A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in negative X – direction . As a result, the charge will

A 10 eV electron is circulating in a plane at right angles to a uniform field of magnetic induction 10^-4 Wb/m² ( =1.0 gauss). The orbital radius of the electron is

A charged particle of charge q and mass m enters perpendicularly in a magnetic field  Kinetic energy of the particle is E, then frequency of rotation 

Current is flowing in a coil of area A  and number of turns N, then magnetic moment of the coil, M is equal to

At what distance from a long straight wire carrying a current of 12 A will the magnetic field be equal to 3 x 10^-5 Wb/m²?

A deutron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 m in a plane perpendicular to magnetic field B.  The kinetic energy of the proton that describes a circular orbit of radius 0.5 m in the same plane with the same B is

A galvanometer of resistance 50 Ω is connected to a battery of 3 V along with a resistance of 2950 Ω in series. A full scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be

A straight wire of length 0.5 m and carrying a current of 1.2 A is placed in uniform magnetic field of induction 2 T.  The magnetic field is perpendicular to the length of the wire. The  force on the wire is

The magnetic field at a distance  r from a long wire carrying current  I is 0.4 T.  The magnetic field at a distance 2r is