Question

The equivalent resistance of a three-resistor combination, consisting of an 18 Ω resistor in series with a parallel combination of 15Ω and 60Ω resistors, (select the best choice) 40Ω 12Ω 26Ω 20Ω 30Ω

Answer 1

To solve this problem, we can use the formula for the equivalent resistance of resistors in parallel and in series.

First, we can find the equivalent resistance of the parallel combination of 15Ω and 60Ω resistors:

1/R_parallel = 1/15Ω + 1/60Ω
1/R_parallel = 4/60Ω + 1/60Ω
1/R_parallel = 5/60Ω
R_parallel = 60Ω/5
R_parallel = 12Ω

Next, we can find the equivalent resistance of the entire circuit:

R_total = R_series + R_parallel
R_total = 18Ω + 12Ω
R_total = 30Ω

Therefore, the best choice for the equivalent resistance of the three-resistor combination is 30Ω.