Hello, As part of a module of a HNC I'm looking at Thevenin's & Norton's Theorems. As it's distance learning and I work full-time it's easier for me to ask on here rather than contact the course lecturer - they're finished by the time I get home and I'm hoping I might get a response to my query faster on here rather than getting involved in an email exchange. I am OK at reducing the various series and parallel resistors to a single resistance but I struggle then to use that to calculate the idea voltage source. As a starting point let's look at this: The answer to which is: . Total resistance = 7+5+((4x6)/(4+6)) = 14.4Ω Current = V/R = 12/14.4 Voltage = IR = 12/14.4 x ((4x6)/(4+6)) = 2V Now I can get that because it's similar to a worked example in the course notes, however I want to know why it's ... x ((4x6)/(4+6)) because when I come to the next question I can calculate the resistance but not to ideal voltage. The next one being: The resistance is 4.5Ω, so the current is (10/4.5)A so the voltage is (10/4.5) x ????? V Thanks.