by Lord Dark
Tags: motor, shunt
P: 121
1. The problem statement, all variables and given/known data
Good evening everyone, I've got the following question :

 A 120-V dc shunt motor having an armature circuit resistance of 0.2 Ω and a field circuit resistance of 60 Ω, draws a line current of 40 A at full-load. The rated full-load speed is 1800 rpm. If the magnetic saturation and armature reaction are negligible, calculate a. The field current, If. b. The full-load armature current, IaFL. c. The full-load back EMF, EbFL. d. The full-load developed power, PdFL. e. The full-load developed torque, TdFL. f. The half-full load armature current, Ia1/2FL(Td1/2FL= 1/2TdFL). g. The half-full load back EMF, Eb1/2FL. h. The motor speed at half-full load, n1/2FL. i. The armature current at the instant of starting, Iastarting. j. The value of the external resistance, Rext that should be connected in series with the armature winding to reduce the starting current to 200% of the full-load current.
2. Relevant equations

3. The attempt at a solution
Lets see,, I solved until part (e) and I didn't understand the rest.
My questions are :
(d)
, does it mean P = E(armature)*I(armature) ?? and BTW the word
 developed
means output ??
(f) what does