The use of eddy currents is done in the following,except:

What is an eddy current? Discuss the practical applications of eddy currents. What should be done to decrease the effects of eddy currents?

What should be the resistivity of materials used for electromagnets,and why?

$A$ coil is suspended in a uniform magnetic field,with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil,it starts oscillating; it is very difficult to stop. However,if an aluminium plate is placed near the coil,it stops. This is due to:

$A$ hollow metal pipe is held vertically and a bar magnet is dropped through it with its length along the axis of the pipe. The acceleration of the falling magnet is ($g=$ acceleration due to gravity).

Discuss the uses of eddy current.