1. The speed of a D.C. shunt motor can be increased by ?increasing the resistance in armature circuit increasing the resistance in field circuit reducing the resistance in the field circuit reducing the resistance in the armature circuit

The speed of a D.C. shunt motor can be increased by increasing the resistance in the field circuit.

Here's why:

1. The speed of a D.C. shunt motor is inversely proportional to the flux per pole. This means that if the flux per pole decreases, the speed of the motor increases.

2. The flux per pole is directly proportional to the field current. This means that if the field current decreases, the flux per pole also decreases.

3. The field current can be decreased by increasing the resistance in the field circuit.

So, by increasing the resistance in the field circuit, the field current decreases, which in turn decreases the flux per pole, and ultimately increases the speed of the D.C. shunt motor.