Answer: 10.
- A 5
- B 10
- C 20
- D 40
Correct answer: B. 10
Explanation: P/Q = R/S. 10/5 = 20/S. 2 = 20/S. S = 10 ohm.
In series, the same current flows through both resistors; in parallel, the current splits between branches and the voltage across each resistor is the same.
Concept context
Ohm's law, resistors, Kirchhoff's laws, Wheatstone bridge, and cells.