- #1

- 59

- 4

- Homework Statement
- The performance of the starter circuit in an automobile can be significantly degraded by a small amount of corrosion on a battery terminal. Figure 26-38a depicts a properly functioning circuit with a battery (12.5-V emf, 0,02 ohms internal resistance) attached via corrosion-free cables to a starter motor of resistance Rs = 0.15 ohms. Suppose that later, corrosion between a battery terminal and a starter cable introduces an extra series resistance of just Rc = 0.10 ohms into the circuit as suggested in figure. Let P_0 be the power delivered to the starter in the circuit free of corrosion, and let P be the power delivered to the circuit with corrosion. Determine P/P0.

- Relevant Equations
- Resistors in parallel/ Resistors in series

The answer sheet assumes that the resistors in both circuits are in series and that we need to use the equation Req = R1+R2+R3.. to find the Req in both cases. How come the resistors are in series, when there are multiple resistors in a single row?

Also, why does the following work yield the wrong answer? The answer should be 0.4, but I keep getting 0.63..

Thank you in advance!