The force experienced by each conductor

The distance of each conductor from the centre of the axis

The number of conductors

The Cross Sectional Area (CSA) of all the conductors

The distance of each conductor from the North Pole of the main magnetic field

Shaft torque = Armature torque - Lost torque

Shaft torque = Armature torque + Lost torque

$Shaft\ torque=\frac{Armature\ torque}{Lost\ torque}$

$Lost\ torque=\frac{Armature\ torque}{Shaft\ torque}$

In a motor an emf is induced in the conductors of an armature as it cuts lines of magnetic flux. This emf opposes the supply voltage.

In a motor an emf is induced in the conductors of an armature as it cuts lines of magnetic flux. This emf enhances the supply voltage.

In a motor an emf is induced in the poles of an armature as current increase in the windings. This emf distorts the main fields magnetic flux.

As supply voltage increases, a capacitance is present between the supply line and the return line of the motor. The discharge of this capacitance is called back emf.

$E_b=V_s-I_aR_a$

$E_b=V_s+I_aR_a$

$E_b=\frac{V_s}{I_aR_a}$

$V_s=\frac{E_b}{I_aR_a}$

The back emf is proportional to the speed of rotation and the strength of the magnetic field

The back emf is proportional to the speed of rotation and the current in the conductor

The back emf is proportional to the number of poles in the main field and the current in the conductor

The back emf is proportional to the supply voltage and the current in the conductor

24^o

15^o

30^o

12^o

The rotor must have an even number of poles

The rotor must have an odd number of poles

There must be more rotor poles that stator poles