Question

A) A conducting rod moves through a magnetic field at a constant speed. Why does the induced potential not continue to increase indefinitely?

B) How can an electric field be produced without any charged objects?

C) A transformer is formed when two coils are placed close enough that the magnetic field of one causes magnetic flux through the second? A changing current in one coil thus induces a current in the second. Why do you suppose transformers are not used in direct current applications? (I.e. when the current doesn't change direction and is more or less a constant value)

Answer 1

C) When the current is changing in  passing through in wire it induced magnetic field. And if the magnetic flux of one coil passing through another it induced emf in another coil. But when the current is constant or not changing then the induced emf in another coil will be gone. This is the same case with direct current(DC) in transformer. Direct current does not change its amplitude is same through out the process. SO THERE IS NO INDUCED EMF IN SECONDARY COIL OF TRANSFORMER beacuse of DC current. i.e transformer are not used in direct current application.

A) The induced potential in the rod is proportional to negative of rate of change of magnetic flux in the rod. When rod passed through the field the induced emf going to decrease away from the field. So, the induced potential can not increase indefinitely because of the negative sign in Faraday law.

B) Electric field can be produced without any charged object is by neutral particle. Uncharged particle are also the source of electric and magnetic field like photon. Photon is uncharged and massless particle it produced electromagnetic field . Electric and magnetic field are perpenducular to each other and can travel at very high speed in space.