1. The problem statement, all variables and given/known data A loop circuit has a resistance of R and a current of 1.8A. The current is reduced to 1.3A when an additional 2.7 ohm resistor is added in series with R. What is the value of R? 2. Relevant equations I is constant throughout a series circuit V is shared in a series Total resistance=the sum of the resistors in series V=I x R 3. The attempt at a solution I substituted R (in the equation V=IR) with 4.7+R because this would represent the total resistance in the series. I knew that I was 1.3A. I calculated the Voltage on the 4.7 resistor (using V=IR) and got 6V. So then I substitued V total with 6 + V. I ended up with the following equation. 6+V=1.3(4.7+R). I then tried substituting V (of the unknown resistor) with 1.3R, but then I realized that couldn't possibly work, because the R's would cancel. Then I tried 1.8R instead so I would end up with the equation .5R=.11, R=.22 but that doesn't sound right.