The electromotive force of the power supply is 12 V, the internal resistance is 1 ohm, R1 = 1, R2 = 6, R1 and R2 are in series, the motor and R2 are in parallel, and the motor resistance is 0.5 ohm The current in the closed circuit is 3a. Calculate the electric power consumed by the motor

The electromotive force of the power supply is 12 V, the internal resistance is 1 ohm, R1 = 1, R2 = 6, R1 and R2 are in series, the motor and R2 are in parallel, and the motor resistance is 0.5 ohm The current in the closed circuit is 3a. Calculate the electric power consumed by the motor

If the total voltage is 12V and the total current is 3a, then R1 shares the voltage of 1 ohm, x3a = 3V, and the internal resistance of the power supply shares the voltage of 3V. R2 and the parallel circuit of the motor share the voltage of 6V, that is, the voltage at both ends of the motor is 6V

As shown in the figure, the resistance R1 = 20 Ω, the motor winding R2 = 10 Ω. When the key s is off, the ammeter indication is 0.5A. When the key s is closed, the motor rotates, the voltage at both ends of the circuit remains unchanged, the ammeter indication I and the electric power consumed by the circuit should be ()
A. I=1.5AB. I＜1.5AC. P=15WD. P＞15W

When the key s is disconnected, according to Ohm's law, u = i1r1 = 10V. When the key s is closed, the current through R1 is still 0.5A, and the current of motor I2 < UR2 = 1010a, so the current of ammeter I < 1.5A, and the electric power of circuit P = UI < 15W. So B is correct. So select B