This results in the following differential equation `RiL(di)/(dt)=V` Once the switch is closed, the current in the circuit is not constant Instead, it will build up from zero to some steady state Solving the DE for a Series RL CircuitOhm's law formula The resistor's current I in amps (A) is equal to the resistor's voltage V in volts (V) divided by the resistance R in ohms (Ω) V is the voltage drop of the resistor, measured in Volts (V) In some cases Ohm's law uses the letter E to represent voltage E denotes electromotive force I is the electrical current flowingThe Ohm's Law formula I = V/R states that V and I are directly proportional for any one value of R Fig 35 Experiment to show that I increases in direct proportion to V with the same R ( a) Circuit with variable V but constant R ( b) Table of increasing I for higher V (c) Graph of V and I
Per Unit System Wikipedia