- #1
BOAS
- 552
- 19
Hello,
i'm unsure of how to complete the final part of this question;
A motor is designed to operate at 118V and draws a current of 12A when it first starts up. At it's normal operating speed, the motor draws a current of 2A. Compute:
a) the resistance of the armature of the coil.
b) the back emf developed at normal speed.
c) the current drawn by the motor at half the normal speed.
I have completed parts a and b.
a) [itex]V = IR[/itex]
[itex]R = \frac{V}{I} = \frac{118}{12} = 9.83 \Omega[/itex]
b) [itex]2A[/itex] flow through the armature with resistance [itex]9.83 \Omega[/itex].
[itex]V = IR = 19.66V[/itex]
Supply voltage = back emf + voltage across armature
back emf = 118 - 19.66 = 98.34V
But how do I figure out c?
Thanks!
i'm unsure of how to complete the final part of this question;
Homework Statement
A motor is designed to operate at 118V and draws a current of 12A when it first starts up. At it's normal operating speed, the motor draws a current of 2A. Compute:
a) the resistance of the armature of the coil.
b) the back emf developed at normal speed.
c) the current drawn by the motor at half the normal speed.
Homework Equations
The Attempt at a Solution
I have completed parts a and b.
a) [itex]V = IR[/itex]
[itex]R = \frac{V}{I} = \frac{118}{12} = 9.83 \Omega[/itex]
b) [itex]2A[/itex] flow through the armature with resistance [itex]9.83 \Omega[/itex].
[itex]V = IR = 19.66V[/itex]
Supply voltage = back emf + voltage across armature
back emf = 118 - 19.66 = 98.34V
But how do I figure out c?
Thanks!