First of all I'd like to say hello. Secondly, my Physics is not very exceptional, so please don't mock me if I ask sth very dumb. :) 1. The problem statement, all variables and given/known data A power station giving an output power of 100kW at 20000V is connected by cables to a factory. If the resistance of the cables is 5.0 Ω, calculate: (a) the current flowing in the cables, 2. Relevant equations P=VI 3. The attempt at a solution I tried solving this using "V=IR". Here's my attempt. V=IR 20000 = I x 5 I = 20000/5 = 4000 A. The actual solution given is: Since P (Output) = IV where I is the current in the cables I=P/V = 100kW/20000 =...= 5A I just need to know why we can't use "V=IR". My guess is it has to sth about a.c. or d.c.