What is the equivalent resistance in the circuit shown in the figure?
A)80 Ω
B)55 Ω
C)50 Ω
D)35 Ω

Question

What is the equivalent resistance in the circuit shown in the figure? 
A)80 Ω 
B)55 Ω 
C)50 Ω 
D)35 Ω

Quizplus · Accepted Answer

To find the equivalent resistance, we need to first simplify the circuit. We can simplify the series resistor combination of 20 Ω and 25 Ω to get a single resistor of 45 Ω. 
Then, we have two more resistors in parallel: 30 Ω and the new combined resistor of 45 Ω. We can use the formula for resistors in parallel to find the total resistance:

1/Rt = 1/30 + 1/45 
1/Rt = (3 + 2)/90 
1/Rt = 5/90 
Rt = 18 Ω

Therefore, the equivalent resistance in the circuit is 18 Ω, which is closest to choice C, 50 Ω.

What Is the Equivalent Resistance in the Circuit Shown in the Figure