A clamp and stand hold a soft-iron bar above a bench. A coil of wire is wrapped round the soft-iron bar. The coil of wire is part of an electric circuit. The figure below shows the arrangement.
Switch S is closed. A student holds a soft-iron disc close to the bar and releases the disc. The disc becomes attached to the bar as shown in the figure above
Explain why the soft-iron disc is attracted to the soft-iron bar.
