Direction :

DC motors have mostly two terminals, across the voltage is applied. When the voltage is applied across these terminals, the motor starts to spin in one direction, and when the polarity of applied voltage is reversed the direction of the rotation is also reversed. Thus, the polarity of applied voltage determines the motor direction, while the amplitudeof voltage determines the speed of motor.

Speed :

The speed of a motor, measured in rotations per minute (rpm), depends on the applied voltage and load.

Voltage :

Each DC motor has a specified voltage that indicates the nominal voltage or the applied voltage that makes the motor run in its normal conditions. In practice, this nominal voltage is important in a project, since it indicates the maximum recommended voltage.

Current :

When a motor is powered at the nominal voltage, the current depends on the load, and increases with load. Therefore, it is important not to allow the motor to run with excessive loads that can stall it.

Power :

A motor’s power is the product of its voltage and current.

Torque :

Torque is defined as the product of the force times the distance from the center of the shaft of a motor.