Electric generators & counter EMF (Back EMF)
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- A motor is connected to a 12V dc supply and draws 5.0A when it first starts up. What will be the back emf when the motor is operating at full speed and drawing 1.2 A?
- 7.0 A
- 7.8 A
- 9.1 A
- 10.8 V
- A motor has an armature resistance of 3.5 and is connected to a 12.0V source. At full speed the current through the armature is 0.18A. what is the back emf at full speed?
- 0 V
- 0.63 V
- 11.4 V
- 12.0 V
- A dc motor is connected to a 12.0V power supply. When the armature is rotating, the current through it is 0.78A and the back emf is 10.6 V. What is the resistance of the armature?
- The load on an electric motor is gradually increased. Which of the following quantities decreases? (Input voltage remains constant.)
- back emf
- armature resistance
- heat produced by armature
- The graph below shows the emf produced by an ac generator Vs. time. At which point in time is the rate of flux change in the generator the greatest?