A proton moving with a constant velocity passes through a Region of space without any change in its velocity. If E vector and B vector represent the electric and magnetic fields respectively . Then the Region of space may be

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?