The correct answer is: A.C. series motor as compared to D.C. series motor has less number of field turns.

A series motor is an electric motor that has the field windings and the armature windings connected in series with each other. This means that the current flowing through the field windings is also flowing through the armature windings. This results in a strong magnetic field that is concentrated around the armature. The armature windings are then cut through this magnetic field, which induces a current in the armature windings. This current then creates a magnetic field of its own, which interacts with the field windings to create a torque that turns the motor.

In a DC series motor, the field windings are made of a large number of turns of thin wire. This is because the DC current flowing through the field windings creates a magnetic field that is proportional to the number of turns of wire. The higher the number of turns, the stronger the magnetic field.

In an AC series motor, the field windings are made of a smaller number of turns of thicker wire. This is because the AC current flowing through the field windings creates a magnetic field that is proportional to the square of the number of turns of wire. The higher the number of turns, the stronger the magnetic field. However, the thicker wire has a higher resistance, which causes the current to flow through the field windings to be lower. This lower current results in a weaker magnetic field.

The weaker magnetic field in an AC series motor means that it has less torque than a DC series motor. This is why AC series motors are typically used in applications where torque is not as important, such as fans and blowers.