$A$ 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 $,A$)

In a $dc$ motor, induced $e.m.f.$ will be maximum:

The output of a dynamo using a split-ring commutator is

$A$ motor operating on $100 \ V$ draws a current of $1 \ A$. If the efficiency of the motor is $91.6 \%$,then the loss of power in units of $cal/s$ is

$A$ rectangular coil of a simple $A.C.$ generator rotates about one of its diameters with a constant angular frequency in the presence of a uniform magnetic field. The direction of the induced current reverses for the third time after how many rotations of the coil?

An $AC$ generator consists of a coil of $500$ turns and area $2\ m^2$ rotating at an angular speed of $30\ rad\ s^{-1}$ in a uniform magnetic field $B = 0.20\ T$ between two fixed pole pieces. The resistance of the circuit including that of the coil is $1000\ \Omega$. What is the maximum current drawn from the generator?