Homework?
The question I'm in doubt about is
The motor coil has a resistance of 10 Ω and is powered by a voltage of 120 V. When the motor is operating at rated speed, its emf is 70 V. Thus, it is questioned:
a) What is the coil current when the motor is started?
b) What is the coil current at rated speed?
What equations can I use to solve it?
Thank you very much in advance
That's a bit harsh - LoL! He was only asking for the formulas...
Ohms Law.... V=IR... Voltage=Currant*Resistance ... Is pretty common when you you see voltage, current and resistance measured.
I'll leave you to research and figure out the correct way to apply these, and whether you're missing anything ( Don't forget to research what back-emf is... )
David.