The current (I) in a circuit is inversely proportional to the resistance (R). I=5 when R=7. Q1. Find the formula for I in terms of R Q2. Fin

I = k / R   (where k is the proportionality constant for this situation.

Given that I = 5 and R = 7:     5 = k / 7    --->     k = 35      (cross multiply)

So this formula is:     I = 35 / R  

                    --->     I · R = 35                    (cross multiply)

                    --->      R = 35 / I                    (divide)