Two resistors R1 and R2 are connected up in a circuit as shown in the figure below.
When the switch S is open, the ammeter reads 1.0 A and the voltmeter reads 8.0 V.
When the switch S is closed, the ammeter reads 1.5 A and the voltmeter reads 6.0 V.
Determine the values of R1 and R2. Show your working clearly.
When the switch S is open, the current only flows through R2.
The circuit can be simplified as shown:
We can calculate the value of R2 directly.
When the switch S is closed, the current flows through both R1 and R2.
We can calculate the resistance across XY:
Since R1 and R2 are connected in parallel and we know the resistance across XY,
Hence, R1 is 8.0 Ω and R2 is 8.0 Ω