DC currents stay above the zero axis and maintain a constant current flow to the motor. This describes currents that are which of the following?

• A. above
• B. below
• C. on
• D. around

Answer: (A)

Direct current flows in one direction and does not cross the zero point on a current-versus-time graph. When the current stays above the zero axis, it means the current is positive and maintains that same direction. The addition of “constant current flow” means the magnitude isn’t changing, so the motor receives a steady, unidirectional current. If it were below the axis, the direction would be reversed; if it crossed the axis or stayed on it, the current would be changing direction or be zero at times. So this situation describes positive, steady DC current.