# Magnetic Effects of Electric Current | Activities in Text Book with Solution

Activity 13.4

Take a long straight copper wire, two or three cells of 1.5 V each, and a plug key. Connect all of them in series as shown in Fig. 13.5 (a).

 Fig. 13.5 (a)

Place the straight wire parallel to and over a compass needle.

Plug the key in the circuit.

Observe the direction of deflection of the north pole of the needle. If the current flows from north to south, as shown in Fig. 13.5 (a), the north pole of the compass needle would move towards the east.

Replace the cell connections in the circuit as shown in Fig. 13.5 (b). This would result in the change of the direction of current through the copper wire, that is, from south to north.

 Fig. 13.5 (b)

Observe the change in the direction of deflection of the needle. You will see that now the needle moves in opposite direction, that is, towards the west [Fig. 13.5 (b)]. It means that the direction of magnetic field produced by the electric current is also reversed.

✅ Answer: If the current flows from north to south, the north pole of the compass needle moves towards the east.

If the current flows from south to north, the needle moves in opposite direction (towards west).

It means that the direction of magnetic field produced by the electric current is also reversed.