I want details about eddy current and rms value of ac.....

Eddy currents are the currents induced in a conductor when placed in a changing magnetic field.

Experiment to explain the origin of eddy currents

Experiment: Place a soft iron core inside a solenoid and connect it to a source of alternating emf. Place a metallic disc over the cross-sectional face of the soft iron core. As the circuit is switched on, the metallic disc is thrown up into the air.

Explanation: When the circuit is switched on, the current starts growing through the solenoid. As the current grows, the magnetic field lines along the axis of the solenoid, and hence the magnetic flux through the disc, also increases from zero to some finite value. Due to this, induced currents are produced in the disc. According to Lenz law, the induced current set up in the disc acts in such a manner that it opposes the increase of magnetic flux through it. As a result, the disc is thrown up.

Applications of Eddy Currents

1. Electromagnetic damping − Some galvanometers have a fixed core, which is made of non-magnetic metallic materials. When the coil oscillates, the eddy currents generated in the core oppose the motion and bring the coil to rest quickly.

2. Induction furnace − In an induction furnace, very high temperature can be produced by producing large eddy currents.

3. Magnetic braking in trains − Strong electromagnets are situated above the rails in some electrically powered trains. When the electromagnets are activated, the eddy currents induced in the rails oppose the motion of the train.

RMS current of AC.

Root Mean Square (RMS) current is the practical unit of AC current which is DC equivalent current of the energy transferred in one cycle of AC.

=> i_rms = 0.707i_o

Thus, rms current of an AC is 0.707 times the peak value of the current.