What effect does reducing the potential difference applied to a motor during the starting period have on the starting torque and the time required to reach speed?

When the potential difference applied to a motor is reduced during the starting period, the starting torque of the motor is affected because the torque generated by a motor is directly related to the voltage applied. A lower voltage results in a weaker magnetic field within the motor, which diminishes its ability to generate torque. Consequently, this leads to a reduction in the starting torque.

As for the time required to reach operational speed, a lower starting torque means that the motor will struggle to overcome inertia and load effectively. This struggle results in a longer time period needed for the motor to accelerate and reach its intended speed. Thus, with reduced torque, the time required for the motor to reach speed increases.

The combination of reduced starting torque and increased time to reach speed explains why the correct answer accurately reflects the effects of lowering the potential difference in a motor during its starting phase.