Post a New Question


posted by on .

At its normal operating speed, an electric fan motor draws only 10.9% of the current it draws when it just begins to turn the fan blade. The fan is plugged into a 120.0-V socket. What back emf does the motor generate at its normal operating speed?

  • PHYSICS 2 !!! - ,

    The current when it "just begins to turn the blade" is a starting surge current. There is no back emf (Vb) at that time. Let R be the resistance of the motor coils.

    The starting surge current is 120V/R.
    The current at normal operating speed is (120 - Vb)/R

    (120 - Vb)/R = 0.109*(120/R)

    Vb = 120 - 13.08 = 106.9 V

Answer This Question

First Name:
School Subject:

Related Questions

More Related Questions

Post a New Question