Automotive Electronics Practice Test

What is the combined resistance of three 12 ohm fuel injectors connected in parallel?

1. 36 ohms

2. 12 ohms

3. 4 ohms

4. 3 ohms

The correct answer is: 4 ohms

To determine the combined resistance of multiple resistors connected in parallel, you can use the formula for parallel resistors. For two or more resistors, the combined resistance (R_total) can be calculated using the following formula: 1/R_total = 1/R1 + 1/R2 + 1/R3 + ... In this case, since all three fuel injectors each have a resistance of 12 ohms, we can substitute these values into the formula: 1/R_total = 1/12 + 1/12 + 1/12 This simplifies to: 1/R_total = 3/12 To find R_total, we take the reciprocal of both sides: R_total = 12 / 3 = 4 ohms. Thus, the combined resistance of the three 12 ohm fuel injectors connected in parallel is 4 ohms. This calculation shows how resistors in parallel reduce the overall resistance, allowing more current to flow through the circuit while maintaining the same voltage across each injector.