The working of magnetic braking of trains is based on

The shiny metal disk in the electric power meter (analog type) rotates due to

The cores used in transformers are laminated 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).

Eddy currents are used in

$A$ metal sheet is placed in a magnetic field that changes from zero to maximum. If the figure shows the direction of eddy currents,then the direction of the magnetic field is: