The working of magnetic braking of trains is based on

In which of the following devices,the eddy current effect is not used?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $A$ bar magnet dropped through a metallic cylindrical pipe takes more time to come down compared to a non-magnetic bar with same geometry and mass.
Reason $R$: For the magnetic bar,Eddy currents are produced in the metallic pipe which oppose the motion of the magnetic bar.
In the light of the above statements,choose the correct answer from the options given below:

$A$ metal detector works on the principle of:

When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical,the final acceleration of the magnet is

Which of the following is not an application of eddy currents?