A circular armature coil is used in a motor with a uniform magnetic field of 2.2

Question

A circular armature coil is used in a motor with a uniform magnetic field of 2.20 T. The coil has a diameter 80 cm, a resistance of 25 , and generates a back emf of 90 VRMS when running a full speed under no load at the angular frequency A.

(A) At what angular frequency, B relative to A does the coil be need to be rotated to generate a back emf of 70 VRMS?

B = _______A

(B) If this motor is operating on 120 VRMS now with a load (e.g running a fan) and at the angular frequency A, how much current is flowing throught the motor?

______A

Explanation / Answer

part a )

70/90 = 0.778

wb = 0.778 wA

part b )

I = (120-90)/25

I = 1.2 A

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.