1=12+13 Loop Rule The sum of the voltage drops Al,across any circuit elements that form a closed circuit is zero: △V=0. (7.5.2) closed loop The rules for determining Al across a resistor and a battery with a designated travel direction are shown below: travel direction travel direction higher V lower V lowerV higher V W W a △V=b-Va=-IR b a b △V='%-'a=+R travel direction travel direction e lower V higher V higher V lower V b Q b △V='b-'a=+e △V='b-'a=-e Figure 7.5.2 Rules for determining potential difference across resistors and batteries. Note that the choice of travel direction is arbitrary.The same equation is obtained whether the closed loop is traversed clockwise or counterclockwise. Example 7.5.1:Voltage divider Consider a source of emf =V that is connected in series to two resistors,R and R R out Figure 7.5.3 Voltage divider. The potential difference,Vo,across resistor R2 will be less than V.This circuit is called a voltage divider.From the loop rule, 7-137-13 1 2 3 I = I + I . Loop Rule The sum of the voltage drops ΔV , across any circuit elements that form a closed circuit is zero: closed loop ∑ ΔV = 0 . (7.5.2) The rules for determining ΔV across a resistor and a battery with a designated travel direction are shown below: Figure 7.5.2 Rules for determining potential difference across resistors and batteries. Note that the choice of travel direction is arbitrary. The same equation is obtained whether the closed loop is traversed clockwise or counterclockwise. Example 7.5.1: Voltage divider Consider a source of emf ε = Vin that is connected in series to two resistors, ￾ R1 and ￾ R2 Figure 7.5.3 Voltage divider. The potential difference, Vout , across resistor ￾ R2 will be less than Vin . This circuit is called a voltage divider. From the loop rule