Who first observed that a current-carrying wire experiences a force when placed in a strong magnetic field?

Why is pure iron not used for making permanent magnets? Name one material used for making permanent magnets. Describe how permanent magnets are made electrically. State two examples of electrical instruments made by using permanent magnets.

Choose the incorrect statement from the following regarding magnetic field lines.

The induced potential difference produced in a coil when a magnet is inserted into it does not depend upon:

Four circular loops of radii $1 \; CM$,$2 \; CM$,$3 \; CM$,and $4 \; CM$ carry the same electric current. At the center of which loop will the magnetic field be the strongest?

Which type of metal or alloy cannot be used to prepare a fuse wire?