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

Under the influence of a uniform magnetic field, a charged particle moves with constant speed v in a circle of radius R. The time period of rotation of the particle.

when a charged particle moving with velocity  is subjected to a magnetic field of introduction , the force acting  on it is non – zero. This implies that 

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

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

Tesla is the unit of

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

The magnetic induction at a point P which is at the distance of 4 cm from a long current carrying  wire is 10^-3 T.  The field of induction at a distance 12 cm from the current will be 

If a long hollow copper pipe caries a current, then magnetic field is produced

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