Automotive Electronics Practice Test

In a 12-volt parallel circuit containing resistors of 4 ohms, 8 ohms, and 16 ohms, what is the total resistance?

1. 4 ohms

2. 8 ohms

3. 2.3 ohms

4. 12 ohms

The correct answer is: 2.3 ohms

In a parallel circuit, the total resistance can be calculated using the formula for resistors in parallel: 1/R_total = 1/R1 + 1/R2 + 1/R3 For the given resistors of 4 ohms, 8 ohms, and 16 ohms, we can substitute these values into the formula: 1/R_total = 1/4 + 1/8 + 1/16 To calculate this, you'd first convert each term to a common denominator, which in this case is 16: 1/4 = 4/16 1/8 = 2/16 1/16 = 1/16 Now, adding these fractions together: 1/R_total = (4/16) + (2/16) + (1/16) = 7/16 Next, to find R_total, we take the reciprocal: R_total = 16/7 Calculating this gives approximately 2.29 ohms, which is commonly rounded to 2.3 ohms. This correctly identifies that the total resistance of the parallel circuit is about 2.3 ohms. The other options do not represent the total resistance in a parallel combination of