$A$ device which converts electrical energy into mechanical energy is

If the rotational velocity of a dynamo armature is doubled, then the induced $e.m.f.$ will become

$A$ motor having an armature of resistance $2\,\Omega$ is designed to operate at $220\,V$ mains. At full speed,it develops a back $e.m.f.$ of $210\,V$. When the motor is running at full speed,the current in the armature is: (in $,A$)

$A$ motor starter:

The armature of a generator of resistance $1 \,\Omega$ is rotated at its rated speed and produces $125 \,V$ without load and $115 \,V$ with full load. The current in the armature coil is ......... $A$.

In an $AC$ generator,the ends of the coil are connected to