1. The problem statement, all variables and given/known data Hello, I am currently doing an investigation to study the factors affecting inductance. The three variables i am using are the number of turns on the coil, the material of the core of the coil and putting 2 cores in series/parallel to see how this affects the inductance in a d.c circuit. now i have done experiments for each whereby i measured V across inductor to allow me to work out I and therefore see the affect on L in L= -ε ÷(dI/dt) i just have a couple of questions though. first of all, am i right in saying that my value for ε (self-induced emf) will the same as the supply voltage? also, i am requesting some help with my theory work deriving the equation for each variable. i have done the theory for changing number of turns by showing how it affects the magnetic flux produced. but im having problems with the other 2 variables i.e. changing the core/parallel & series circuits; where/what equation with should i start? Any help hugely appreciated. Thanks for your time.