To understand the working of an electric fuse, take a thin strip of aluminium foil about 5 cm in length. Fix its two ends on the tips of the two iron nails placed vertically on the table. Connect the two nails to a battery through a plug key and a small bulb, as shown in Fig.

Fig. Action of electric fuse
As we switch on the circuit, the aluminium strip burns out immediately. The circuit breaks and current stops flowing. This is how an electric fuse works using the heating effect of current.