Three resistors of 1.5 Ω, 0.05 Ω and 0.25 Ω are connected in series. The…

When resistors are connected in series, the same current flows through every resistor in the circuit, and the equivalent (total) resistance is simply the sum of the individual resistances: Req = R1 + R2 + R3. This is different from a parallel combination, where reciprocals of the resistances are added instead of the resistances themselves.

1. Identify the given series resistances: R1 = 1.5 Ω, R2 = 0.05 Ω, and R3 = 0.25 Ω.

2. Write the series-equivalent-resistance formula: Req = R1 + R2 + R3.

3. Substitute the given values into the formula: Req = 1.5 Ω + 0.05 Ω + 0.25 Ω.

4. Align the decimal points of all three numbers and add them: 1.50 + 0.05 + 0.25 = 1.80.

5. Therefore, the equivalent resistance is Req = 1.80 Ω.

As a check, add the same three numbers in a different order: (1.5 + 0.25) + 0.05 = 1.75 + 0.05 = 1.80, which matches. Also, the equivalent resistance of resistors in series must always be at least as large as the largest individual resistor (1.5 Ω here); 1.80 Ω satisfies this, confirming the result is reasonable.