KitsGuru Finding Polarity of an electromagenet LGSK032 Educational Electronic Hobby Kit

This circuit can be used to to demonstarte two concepts. One is , how the electric current can induce a magnetic filed, and secondaly how the polarity of an DC supply can be reversed by using four switches. If any current flows through any coil made of conductors(gnerally copper), then a magnetic field will be induced. The direction can be checked by using a metal or a piece of magnet. If the direction of the current is reversed, then the direction of the induced filed will also be reversed. In the given circuit let us suppose we have opende switches S2,S4 and closed the switches S1,S3. Clearly the current will flow from V2 to V3. Now if we open S1, S3 and close S2,S4 , clearly the current will flow from V3 to V2