Final answer:
The equation to find the equivalent resistance of two resistors in series is Req = R1 + R2. Adding resistors in series increases the overall resistance in the circuit.
Step-by-step explanation:
The equation to find the equivalent resistance, Req, of two resistors in series, R1 and R2, is:
Req = R1 + R2
This means that the equivalent resistance is simply the sum of the individual resistances in the series circuit. When resistors are added in series, the overall resistance in the circuit increases because the current has to flow through each resistor sequentially, which results in an increased total resistance.