- #1
marpple
- 30
- 0
A motor with a brush-and-commutator arrangement has a circular coil with radius 2.5 cm and 150 turns of wire. The magnetic field has magnitude 0.06 T and the coil rotates at 440 rev/min.What is the average back emf?
i have tried this
Flux=Magnetix Field*Area
Flux=0.06*pi*r^2
Here r=2.5cm=2.5*10^-2m
Avarage Emf=N*Flux/Time
Time=1/Speed
Speed=440 rpm=440/60=7.3333
Average Emf=Flux*150/Time
so average Emf = 0.06*phi*r^2*150 / 0.136363 = 0.1295 V
but, my answer is wrong..
please advise!
i have tried this
Flux=Magnetix Field*Area
Flux=0.06*pi*r^2
Here r=2.5cm=2.5*10^-2m
Avarage Emf=N*Flux/Time
Time=1/Speed
Speed=440 rpm=440/60=7.3333
Average Emf=Flux*150/Time
so average Emf = 0.06*phi*r^2*150 / 0.136363 = 0.1295 V
but, my answer is wrong..
please advise!