Write down working of electric motors …

Working

• When the current begins to flow, current flows through brush X, then A to B, B to C, C to D and then to brush Y and into the battery.
• Now applying Fleming's Left Hand Rule to wire AB, Current is along AB, Magnetic Field is as shown (North-> South), the motion of the wire is downwards.
• Now applying Fleming's Left Hand Rule to wire CD, Current is along CD, Magnetic Field is as shown (North-> South), the motion of the wire is upwards.
• The rectangular coil begins to move in the anti-clockwise direction
• Note that during anti-clockwise motion, the split rings and axle also move, whereas the brushes don't move.
• After half a rotation, Wire CD and Split ring Q moves to the left.  Wire AB and Split ring P moves to right. Brushes X and Y donot move.
• Now applying Fleming's Left Hand Rule to wire CD, Current is along DC. (Battery -> Split ring Q -> DC , Magnetic Field is as shown (North-> South), the motion of the wire is downwards.
• Now applying Fleming's Left Hand Rule to wire AB, Current is along BA. (Battery -> Split ring Q -> DC --> CB -> BA --> Split ring P) , Magnetic Field is as shown (North-> South), the motion of the wire is upwards.
• So, again the coil rotates in the anti-clockwise direction.
• The reversal of current in the coil results in the continous rotation of the coil. The reversal of current is achieved by the commutator rings