Set up the circuit shown in Fig. 14.17 again. Move the key to ‘ON’ position and watch careful in which direction the compass needle gets deflected. Switch ‘OFF’ the current. Now keeping rest of the circuit intact, reverse the connections at the terminal of the cell. Again, switch ‘on’ the current. Note the direction in which the needle gets deflected. Think of an explanation.

On reversing the connections of cell, the direction of deflection of needle will also gets reversed because the polarity of magnet is dependable on the current direction in which it is flowing.