《电路基础》样卷–答案(学习).docVIP

Solve the following problems. (100 points) 1、( 6 points) Find Uab in the circuit in Figure 1. Solution: Uab= 9V 2、( 8 points) Find uo and io in the circuit in Figure 2. Solution: , 3、( 6 points) In the circuit of Figure 3, readings of voltmeter ， and are 10V, 18V and 6V, respectively. Please determinate the reading of the voltmeter . Solution: The reading of the voltmeter is 10V. 4、( 8 points) The resonant or tuner circuit of a radio is portrayed in Figure 4, where us1 represents a broadcast signal, given that R=10Ω，L=200μH, Us1rms=1.5mV，f1=1008kHz. If the circuit is resonant with signal us1, please determinate: (1) the value of C; (2) the quality factor Q of the circuit; (3) the current Irms; (4) the voltage Ucrms. Solution: 5、( 8 points) A balanced three-phase circuit is shown in Figure 5. Calculate the phase currents and voltages in the delta-connected load Z, if , Z=(24+j15)Ω，ZL=(1+j1)Ω. Solution: , 6、( 8 points) Find the y parameters for the circuit in Figure 6. Solution: 7、( 15 points) For the circuit in figure 7, find the rms value of the current i and the average power absorbed by the circuit, given that , ,,,. Solution: P=P0+P1+P2=256+333.28+50=639.28W 8、( 12 points) In the circuit of Figure 8, determinate the value of Z that will absorb the maximum power and calculate the value of the maximum power. Solution: If , Z will absorb the maximum average power. The maximum average power is, 9、( 14 points) If the switch in Figure 9 has been closed for a long time and is opened at t = 0, find uc, iL, uk for t ≥ 0. Solution: ， 10、( 15 points) The switch in Figure 10 has been in position a for a long time. At t = 0, it moves to position b. Find i2(t) for t ≥ 0 and sketch it. (Attention: Please mark the key data in your graph.) Solution: