Production of back emf in the armature
The current drawn by a 120 V dc motor with back emf of 110 V and armature resistance of 0.4 ohm is 25 A.
Back emf increases but line current falls
If the back in a dc motor vanishes suddenly, the motor will burn.
Coupling mounted on the shaft
All of the above
Output power at the shaft
The output indicated on the name plate of any motor is always the Output power at the shaft.
Both (b) and (c)
A thicker wire is used in dc series motor filed winding than that in a dc shunt motor To reduce resistance and to carry large load current.
In series with the armature winding
In case of a conductively compensated dc series motor, the compensating winding is provided In series with the armature winding.
The dc compounded motors are generally Cumulative compounded motor.
Control the flux
In a dc compound motor, the filed regulator is provided to Control the flux.
Fleming left hand rule
The direction of rotation of a dc motor can be determined by Fleming left hand rule.
Either field or armature terminals
The direction of rotation of a dc shunt motor can be reversed by interchanging Either field or armature terminals.
The motor will run at its normal speed in the same direction as before
When the supply terminals of a dc shunt motor are interchanged, the motor will run at its normal speed in the same direction as before.
By interchanging field terminals
The direction of rotation of a dc series motor can be reversed By interchanging field terminals.
directly proportional to it back emf and inversely proportional to flux
The speed of a dc motor is directly proportional to it back emf and inversely proportional to flux.
increase by 5%