What type of core is used to make an electromagnet?

Draw a diagram to show how a magnetic needle deflects when it is placed above or below a straight conductor carrying current,depending on the direction of the current in the conductor.

If a circular loop is made of $6$ closely wound turns instead of a single turn,the magnetic field produced at the center of the loop becomes $.........$ times stronger.

$A$ constant current flows in a horizontal wire in the plane of the paper from east to west as shown in the figure. The direction of the magnetic field at a point will be North to South:

Describe an activity to show that the magnetic field produced by a given current in a wire decreases as the distance from the wire increases.

The strength of the induced potential difference depends on the relative speed between the coil and the magnet.