If R1 = 2 Ω and R2 = 10 Ω are connected in series, what is the total resistance?

If R1 = 2 Ω and R2 = 10 Ω are connected in series, what is the total resistance?

• A. 2 Ω
• B. 10 Ω
• C. 24 Ω
• D. 1 Ω

Answer: (B)

When resistors are in series, the same current flows through each component, so their resistances simply add. Total resistance = R1 + R2. Here that’s 2 Ω + 10 Ω = 12 Ω. In series, the opposition to current is the sum of all resistances, which is why you add them directly. (In case you’re curious, if these were in parallel, you’d use the reciprocal rule 1/R = 1/2 + 1/10.) The essential point is that series resistances add to give the total.

When resistors are in series, the same current flows through each component, so their resistances simply add. Total resistance = R1 + R2. Here that’s 2 Ω + 10 Ω = 12 Ω. In series, the opposition to current is the sum of all resistances, which is why you add them directly. (In case you’re curious, if these were in parallel, you’d use the reciprocal rule 1/R = 1/2 + 1/10.) The essential point is that series resistances add to give the total.