In the circuit, the resistance R1 is 10 Ω. Close the switch s, the indication of ammeter A1 is 0.3A, and the indication of ammeter A2 is 0.5A Ask: (1) current through resistance R2: (2) power supply voltage please write the process of solving the problem clearly

In the circuit, the resistance R1 is 10 Ω. Close the switch s, the indication of ammeter A1 is 0.3A, and the indication of ammeter A2 is 0.5A Ask: (1) current through resistance R2: (2) power supply voltage please write the process of solving the problem clearly


Because the two meters show different numbers, it is a parallel circuit
The voltage is 10 * 0.3 = 3V
So the current of R2 is 3 / 0.5 = 6 Ω
I haven't studied physics for three or four years, right



As shown in the figure, the resistance R1 = 12 Ω. When the key SA is off, the current passing through is 0.3 A; when the key SA is closed, the ammeter shows 0.5 A. Q: what is the power supply voltage? What is the resistance value of resistance R2?


When the key SA is closed, the circuit is a simple circuit of R1, and the voltage of the power supply is u = i1r1 = 0.5A × 12 Ω = 6V; when the key SA is disconnected, the two resistors are connected in series, and the total resistance of the circuit is r = UI = 6v0.3a = 20 Ω, R2 = r-r1 = 20 Ω - 12 Ω = 8 Ω. Answer: the voltage of the power supply is 6V, and the resistance of R2 is 8 Ω