Question

1. when calculating r_th in a simple circuit, you ________. a reconnect the source and use this formula: r_th = (r1 + r2)/(r1 x r2) b short the source and use this formula: r_th = (r1 x r2)/(r1 + r2) c reconnect the load resistor and use this formula: r_th = v_th/rl d make an imaginary chassis ground

Explanation:

Step1: Recall Thevenin resistance concept

To find the Thevenin resistance ($R_{TH}$) in a simple - circuit with two resistors in parallel, we first need to short - circuit the independent voltage source (or open - circuit the independent current source). When we have two resistors $R1$ and $R2$ in parallel, the formula for $R_{TH}$ is $R_{TH}=\frac{R1\times R2}{R1 + R2}$.

Answer:

B. short the source and use this formula: $R_{TH}=\frac{(R1\times R2)}{(R1 + R2)}$