1. The problem statement, all variables and given/known data 2. Relevant equations Please review the question and answer of question 34. 3. The attempt at a solution 1.Why does the answer take the rated power as the power output? 2.I tried to find the current like this: R=200^2 / 100 = 400 ohm I at Q = 400/[2(400)] = 0.5 A I at P = 0.5/2 = 0.25 A 3. As the approach as shown as (2) is wrong. Either V is not equal to IR in the circuit Q or the secondary voltage is not 400/2 = 200V. 4. As question 36 used a similar method as (2), V should be equal IR. So the only possibility is Vq not equal to Vp [Nq/Np]. 5. However as the change of magnetic flux is the same everywhere in the iron core. By V=-NdΦ/dt. Vp=- Np dΦ/dt....(a) Vq=- Nq dΦ/dt....(b) Vr=- Nr dΦ/dt....(c) by (b)/(a) Vq = Vp [Nq/Np] 6. So please tell me what's wrong. Thank you VERY much.