Physics for IGCSE & O level - Electricity (Section 9 - No. 49)

What is the total resistance of two resistors (10 ohms and 20 ohms) connected in parallel?

30 ohms

15 ohms

6.67 ohms

10 ohms

For parallel resistors, calculate: 1/Rt = 1/R1 + 1/R2. Thus, 1/Rt = 1/10 + 1/20 = 3/20. So Rt = 20/3 which is approximately 6.67 ohms.